Lecture 14: Centrality of Christ and God in Paul's Theology
Course: Biblical Theology
Hello. I am Tom Schreiner and I teach New Testament at the Southern Baptist Theological Seminary in Louisville Kentucky. I am also the preaching pastor at Clifton Baptist Church. And I will be giving these lectures on Pauline Theology in five hours.
I. The Basic Claim
When we think of Pauline theology, I think we need to focus on what is most important in Paul's theology. And the focus, I would argue, is on God and Jesus Christ. Paul's theology is God-centered and Christ-centered. We think here of Romans 11:36, speaking of God: "For from Him and through Him and to Him are all things." So, Paul's theology is focused on God, the One from whom all things come and through whom all things are accomplished. And ultimately all things are for His glory. In Pauline theology God is the center of that theology.
But God, in Pauline theology, is magnified in Jesus Christ. God's centrality is manifested in Christ. So it is not as if God and Christ are separate, but God and Christ work together in Paul's theology. We think here of 1 Corinthians 8 :6, where Paul says: "Yet for us, there is one God, the Father, from whom are all things and for whom we exist." So, all things come from God and all things are for God's glory. We exist for Him. "And one Lord, Jesus Christ, through whom are all things and through whom we exist." So we see there that Paul puts God and Christ together as equally significant and central.
a. The Preeminence of Christ
If we think further about Paul's theology, we can see that Christ is preeminent in his theology. We think here of Colossians. Christ is the image of God. He reflects who God is. He is the firstborn of all creation. That does not mean that He is the first creature, but He is sovereign over all creation. He is the Creator of all. All things are created by Him and for Him (Col.1:16). But if something is created by Christ, by His agency and for His glory, then Christ is magnified in the creation. He is before all things and in Him all things hold together (Col.1:17). Christ is the Head of the church (Col.1:18). So again we see His centrality. He is to be preeminent in everything (Col.1:19).
Paul is dramatically Christ-centered, isn't he? He says, in thinking about conversion: "As you receive Christ Jesus the Lord, walk in Him" (Col.2:6). Conversion is receiving Christ as Lord. In Colossians, the false teachers go astray because they do not teach according to Christ. They move their hearers and converts away from Christ. We learn that all the fullness is in Christ and you are complete in Him (Col.2:9-10). So the only way to completion – the only way to fullness, the only way to satisfaction – is in Christ. There is no other way. Christ is glorified in that the fullness of believers is realized as believers rest in Him.
Paul says: "Think on the things above where Christ is" (Col.3:1). The fullness of God comes when we reflect on Christ. Your life is hidden with Christ in God and Christ is our life (Col.3:3-4). It is truly stunning, isn't it, how focused on Christ Paul is in his theology? God is glorified; God is magnified; God is lifted up when Christ is central.
Of course, Paul's probably most full and detailed explanation of his gospel comes in the book of Romans. Paul introduces in that book the gospel of God – the fulfillment of the Old Testament Scriptures. And that gospel, he tells us, is the gospel concerning His Son. What is the good news about? What does the good news focus on? The good news focuses on the Son, Jesus Christ. He is central in Pauline theology. He is the main issue. He is the main person. God has so arranged the history of His saving purposes so that Jesus would be praised.
In the book of Galatians, we have false teachers who are arguing that believers must obey the law and be circumcised to be saved. That troubles Paul greatly, because it compromises the centrality of Christ and His cross. He argues that if righteousness comes by the law then Christ died for nothing (Gal.2:21). The problem with the law-based and circumcision-based gospel is that it diminishes the importance of what Christ has done and the importance of Christ's cross. Galatians 3:1 says: "O foolish Galatians! Who has bewitched you before whose eyes Jesus Christ was publicly proclaimed as the crucified one?" So again, the problem with the false-teachers' gospel is that it does not focus on Christ and His cross. It takes away from the atonement that Jesus has accomplished.
The blessing of Abraham, Paul tells us, comes through Christ (Gal.3:14). There is only one seed of Abraham and that seed of Abraham is Christ (Gal.3:16). If one is going to belong to the family of Abraham, one needs to be incorporated in the Christ to belong to Christ. He is the only pathway to the blessing of Abraham. Paul says the law is our pedagogue (Gal.3:24). The law is our tutor. The law is our guardian until the time of Christ. So the Mosaic Law was meant to be enforced for a certain period of salvation history. And now that Christ has come, we are no longer under the law. All of the Old Testament points to Jesus and climaxes in Him and focuses on Him.
4. 1 Corinthians
We see the same thing in 1 Corinthians. We see the centrality of God and Christ in Corinth. The Corinthians have gone astray because they have forgotten about Christ and Him crucified. That is the message that Paul teaches in 1 Corinthians 1:17-18. He proclaims the word of the cross. He preaches Christ crucified and he preaches that so that the Corinthians and all of us will boast only in the Lord (1:23). We are not to boast in ourselves and what we have accomplished and our obedience to the law – our wisdom, our might, our strength. But God has chosen us in Christ for salvation so that we would boast only in the Lord and not boast in anything or anyone else. Paul says: "I determined to know nothing among you except Jesus Christ and Him crucified" (1 Cor.2:3). The message of the cross is the message of Christ crucified and His great work.
What I am arguing here, over and over again, is the centrality of Christ in Paul's theology. And I am just showing you this in a lot of verses. In the book of Philippians, Paul rejoices when people preach Christ (1:18) – the joy of the proclamation of Jesus Christ. Paul says: "For me to live is Christ and to die is gain" (1:21). I think it is clear there what is central in Paul's theology is Jesus Christ, because to live, Paul says, is Christ and to die is gain. Nothing is more important for Paul than Jesus Christ and to live for His glory and praise and honor. In fact, the greatest thing for Paul would be to die, because if he were to die he would be with Christ and that is his goal. That is his longing.
6. 2 Corinthians
All of God's promises (now I am moving to 2 Corinthians), all of God's promises are "yes and amen in Christ" (2 Cor.1:20). Again, we see the centrality of Jesus in that all the Old Testament climaxes in Him. All the Old Testament points to Him and finds its fulfillment in Him. We also see that the glory of Christ outshines the glory of Moses and the law (2 Cor.3:10-11). There was glory in the giving of the law and on the face of Moses. But the glory of Christ outshines the glory of Moses. The glory of Christ is like the glory of the sun and the glory of Moses is like the glory of the moon. There was glory on Moses' face, but the glory of Christ exceeds Moses' glory. And it shines brighter and truer so the glory of Moses always pointed to Christ and His glory so that He would receive the praise and honor forever.
That fits with 2 Corinthians 2:4-6. There Paul speaks of the God of this world (Satan), who has blinded the minds of unbelievers to keep them from seeing what? To keep them from seeing the light of the gospel of the glory of Christ. What unbelievers do not see is that Christ is glorious – that He is beautiful; that He is wonderful. Satan blinds unbelievers from seeing that. So they think Christ is not exciting or glorious or beautiful or the reason for living. Satan blinds people from seeing that.
The glory of Christ who is the image of God – we already saw that in Colossians, that Jesus is the image of God. Paul says: "For what we proclaim is not ourselves." And that is true of all of us as Christian ministers. We do not proclaim ourselves, do we? We do not proclaim our own wisdom and strength. We are weak and sinful in and of ourselves. "But we proclaim Jesus Christ as Lord, with ourselves as your servants for Jesus' sake." So God calls us not to proclaim ourselves and our wisdom and our might, but Jesus.
And then we see in 2 Corinthians 4:6 – "For God, who said let light shine out of darkness." And where did God say that? God said that in Genesis 1:3, didn't He? It was on the first day of creation. Where the world is covered with darkness, God said let the light shine out of that darkness. Let it blaze out of that darkness. But now He has shown in our hearts to get the light of the knowledge of the glory of God. So now we see the glory of God where? We see it in the face of Jesus Christ. Verse 4 spoke of the glory of Christ. Now Paul speaks of the glory of God in the face of Jesus Christ. So, we see again that God's glory is maximized – God's glory is manifested; God's glory is realized – in Jesus Christ (in the face of Jesus Christ).
b. The Glory of God and the Glory of Christ
In 1 Corinthians 10:31, we read that we are to do all things to the glory of God, whether we eat or drink or whatever we do. We are to do it for the glory of God. But doing those things for the glory of God does not cancel out the glory of Christ. We read in Colossians 3:17 – "In whatever you do in word or deed, do everything in the name of the Lord Jesus, giving thanks to God the Father through Him." So, we read in 1 Corinthians 10:31 that whether we eat or drink or whatever we do, we are to do it for the glory of God. But another way of saying the same thing is what we find in Colossians 3: 17 – whatever we do, whether it is in word, whether it is in speech or action, we are to do everything in the name of the Lord Jesus, giving thanks to God the Father through Him. So, do everything for the glory of God. Another way of saying that is to do everything in the name of Jesus. We see again that Jesus is maximized – Jesus is praised; Jesus is honored – when God is glorified. There is no conflict between the glory of God and the glory of Jesus.
1. The Failure to Honor God is the Root Problem
In Romans 1:18-25 (we will see this again later), what is root sin? The root sin is the failure to give glory to God. The failure to honor and praise and esteem God as we should, that is the very heart of sin. Sin detracts from God's glory. Sin is a failure to be God-centered, to rely on Him. Romans 14:23 says: "Whatever is not of faith is sin." So sin is a failure to trust God in everything. In Romans 4:19, we see that faith gives glory to God, trusting that His word is reliable. Sin is a failure to trust God. Whatever is not of faith is sin. Sin is a failure to see that God is strong. Sin is a failure to believe that He will do what He promised. The root issue in all of life is always: Are we glorifying and honoring God? Sin does not glorify and honor God, because it does not view Him as trustworthy. Sin does not believe that God would satisfy us. Sin looks to other gods to protect us and satisfy us and keep us safe. But faith glorifies God by trusting Him to protect us and Him alone and not looking to any other idols or any other helps or any other totems or fetishes, but only trusting in God. Faith is not trusting in our wisdom or our money or our reputations, but only in God.
2. Honoring God with our Bodies
In 1 Corinthians 6, Paul talks about the need to be sexually pure and not to commit sexual sin. Obviously, we see in Scripture that we are only to engage in sexual relations when we are married, with our spouse. So we glorify God with our bodies (1 Cor.6). We glorify God with our bodies by doing with our bodies what God has commanded us to do, and not sinning against Him and doing what He has forbidden us to do.
3. Honoring God with our Money
In Philippians 4, we see that we glorify God with our money when we give as He has commanded us. When we are generous, we glorify God. When we trust Him, we can help others who are in need. Because Paul says: "And my God will supply every need of yours according to His riches in glory in Christ Jesus" (Phil.4:19). God has promised to supply our needs and we glorify Him in the midst of this by giving our money to others. We trust that God will supply our needs. And since He has promised to supply our needs, we generously give to others and we do not hoard money for ourselves. That is in Philippians 4.
4. Honoring God in our Relationships
Romans 15:7 says we are to glorify God by accepting one another – by loving one another; by receiving one another; by having fellowship with one another. In Ephesians 5:22 and following, where Paul speaks of the relationship between husbands and wives, he emphasizes that we do everything in Christ. We do everything in the Lord. We do everything to bring Him praise and honor and glory. Wives do not just submit to husbands because it is the right thing to do and husbands do not merely love their wives and sacrifice for them because it is the right thing to do. It is the right thing to do, but we do so because it glorifies and honors God – because God receives praise when we do that.
5. Finding our Satisfaction in God
In Romans 5:11, where Paul speaks of the great salvation we have received, he ends by saying we boast in God in Jesus Christ. We exalt in God – we find our satisfaction in God; we glorify God – by enjoying Him. We glorify God by finding Him to be our all in all. We glorify God by exalting in Him – boasting in Him; rejoicing in Him. So, glorifying God is not just an abstract idea. It is something practical and useful for our everyday lives.
c. God's Great Work for us in Christ
In Ephesians 1:3-14, Paul speaks of the great work that is done for us by God. God has elected us before the foundation of the world to be saved. God has redeemed us. God has disclosed the plan of all of salvation history in Christ. God has given us of His Spirit. But what he says over and over again is: He has done all of this in Christ, in Him. You can just read those verses and see over and over that what God has done, He has done for us in Christ. So again, Christ is the focus in those verses.
Maybe I should read some of those. He has blessed us in Christ with every spiritual blessing in the heavenly places. He chose us in Christ, in Him (Eph.1:4). We are to be holy and blameless before Him. He predestined us for adoption as sons through Jesus Christ (1:5). He blessed in the beloved, who is Jesus Christ (1:6). In Christ, we have redemption (1:7). The mystery of His will He set forth in Christ (1:9). The plan for all the fullness of time was to unite all things in Christ (1:10). In Him, we have an inheritance in Christ (1:11). He speaks of those who hope in Christ (1:12). In Him, we were sealed with the Spirit (1:13). So, you can see very clearly that Christ is very central in the book of Ephesians and in these first verses.
We see later on in the chapter that Christ rules over all authority and power. If you will look at Ephesians 1:20 – "God worked in Christ when He raised Him from the dead and seated Him at His right hand in the heavenly places, far above all rule and authority and power and dominion and above every name that is named, not only in this age but also in the one to come. And He put all things under His feet and gave Him as head over all things to the church which is His body, the fullness of Him who fills all in all." So Christ rules over all demonic powers, over all angels, over all things. He is the Sovereign One.
We see also Ephesians 2:7 the centrality of God and Christ. It says there that God's whole plan in the history of salvation is that in the coming ages He might show the immeasurable riches of His grace and kindness toward us in Christ Jesus. So what will we be doing through all eternity? We will be praising God for the immeasurable riches of His grace that He showed us in Christ. We already saw in chapter 1 that all of salvation history is united in Christ. God's whole plan was to focus on Christ. And so here we see the riches of God's grace in Christ is what we will praise for all of eternity. We will be focusing on what God has done for us. God's salvation is described in Ephesians 3:8 as the unsearchable riches of Christ. And through the church God's manifold wisdom is made known (3:10). The rulers and authorities and the demons will see God's great saving purposes that have been accomplished in Jesus Christ. So, you can see how crucial Christ is.
d. Spreading the Knowledge of Christ
Paul's whole goal is to bring the knowledge of Christ to others. And I think it is helpful for us to see then, when we think of Paul's theology, that Paul is a missionary. Paul's goal is to bring the knowledge of Christ to others, especially to the Gentiles. Paul's joy in life and the joy of all in ministry is to spread the knowledge of Christ to others.
1. Paul's Testimony of Conversion
He emphasizes, doesn't he, in his letters that he was unworthy? We think of 1 Corinthians 15:9 and following and 1 Timothy 1:12 and following and Ephesians 3:1 and following. Paul emphasizes that, as a missionary, he was unworthy. Because he persecuted the church of God, he was not worthy to be a missionary. But God had called him. God's grace had worked in him. On the Damascus Road, God summoned Paul to faith in Jesus Christ. And he summoned him to be the apostle to the Gentiles.
That is very clear, isn't it, in the book of Galatians – that God's supernatural work is what changed Paul? We see in Galatians 1:11 – "For I would have you know brothers that the gospel that was preached by me is not man's gospel." Paul did not preach a human gospel. He did not receive it from any man (1:12). No man explained the gospel to him – "nor was I taught it, but I received it through a revelation of Jesus Christ." Jesus Christ appeared to him on the Damascus Road. "You have heard of my former life in Judaism, how I persecuted the church of God violently and tried to destroy it." Before Paul was converted, he tried to rule out the Christian faith and opposed it violently. And he was advancing in Judaism beyond many of my own age, among my own people, so extremely zealous was I for the traditions of my fathers. Paul was a very ardent Jew and observant of the law, before he was saved. But God intervened, didn't he? And God turned him around. We see in verse 18: "But when He would set me apart before I was born", that is God. God had called Paul before he was born to be an apostle. And he called Paul by His grace. Again, that is on the Damascus Road.
What can account for Paul's conversion? He was absolutely convinced, wasn't he, that Jesus Christ was not the Messiah? He was convinced that Jesus was a pretender. And therefore he persecuted the church and tried to destroy it. He was absolutely convinced that he was right. But he understood, didn't he, that he was dramatically wrong? And he was turned around by God's grace. When God called him, God was pleased to reveal His Son to Paul supernaturally on the Damascus Road – when Jesus Christ appeared to him and spoke to him and commissioned him to be an apostle. And He did so, so that he would share the good news with Gentiles – the good news of the gospel. His call to apostleship was supernatural, even when he was unworthy.
2. Paul's Testimony of his Missionary Goal
Paul's missionary goal was to preach the gospel. We see that in Romans 1:14-15, Colossians 1:25 and 1 Corinthians 9. That was the passion of his life: to preach the gospel. And we know that he endured persecution and difficulty and suffering and people attacked him for his apostleship. This was no easy matter. Paul did not live a comfortable life, but he was willing to suffer all things for the sake of the gospel – for proclaiming the gospel and for bringing it to others.
It took extraordinary effort. We read about it in Colossians 1:28-2:3. And we know that it was plagued by suffering. We read in 2 Corinthians 11 all of the difficulties that Paul experienced. The proclamation of the gospel was no easy task, but for Paul it was a joyous task because that is what God had called him to do. And he imitates Christ. He is not Christ, of course. But he imitates Christ in that he also endures suffering. Only Christ's death is atoning and brings forgiveness of sins. And, of course, Paul's suffering is not like that. But Paul's suffering does replicate Christ to some extent. It is the means by which the message of the gospel goes out to others, so that others can be included in God's saving purposes.
So, the message of the gospel – the suffering that Paul undergoes as one who is called and converted on the Damascus Road – that message of the gospel is shown to be precious precisely because Paul suffers. His suffering shows the preciousness of the gospel and that he is willing to give all so that the gospel would go forth.
3. Paul's Testimony to the Gentiles
The other interesting thing about Paul is Paul is called to be an apostle to the Gentiles. We might think with Paul's Jewish background and training in the Scriptures and his work as a Pharisee that God would call him to be an apostle to the Jews. But God is sovereign. God chose Paul and called Paul and elected Paul to bring the gospel, not to the Jews, but to the Gentiles – to bring this gospel to the ends of the earth. Paul says in Romans 15:16 that he has a sort of priestly call to bring this gospel to the Gentiles. And that is an issue that Paul often defends in his letter – that the gospel is bringing the good news to the Gentiles.
As a Jew he must defend the bringing of the gospel to the Gentiles. He must show that this is theologically right, because some of the Jews believe that the good news was only for them. They believed that it was restricted to a single people group. And Paul wants to make clear that that is not the case. The gospel is for all people – not only the Jews, but also to the Gentiles. The gospel goes to the very ends of the earth and it cannot be restricted only to the Jewish people. Paul has to theologically defend that, of course. And he does that. He shows that the inclusion of the Gentiles is a fulfillment of God's saving purposes.
Before the coming of Christ, of course, the Gentiles are not part of God's covenant people. That is very clear in Ephesians. Previously the Gentiles are the uncircumcised. They are outside God's covenant. They are separated from Christ (Eph.2:12). They are alienated from the commonwealth of Israel. They are not part of Israel. They are not part of Christ. They are strangers to the saving covenants of promise. They have no hope, no salvation and they are without God in the world. That was the state of the Gentiles before the coming of Christ. Paul does not view them as being saved.
But it is so important to share the glory and beauty of God in Christ, because it is necessary for salvation and for knowing Christ and loving Christ and serving Christ. It is all, for Paul, about Christ. And now, in Christ Jesus, the Gentiles are near. They are no longer separated from God's promises through the cross of Christ if they put their faith in Him. Paul does not think of the Gentiles as saved before Christ came, but he argues instead that the enmity between Jews and Gentiles is removed in the cross of Christ. The Gentiles are not automatically saved now that Christ has come. They need to be reconciled to God in Christ. They need to know about what Christ has done for them, and that is why Paul engages in missions. Missions is so important because it focuses on what Christ has done and brings Him all the glory and honor. And that good news is shared through him.
We think here of Colossians 1. This is the passion of Paul's life: the mystery that was hidden for ages and generations, but is now revealed to His saints. And that is the riches of the glory of Christ being in you. And that was the passion of Paul's life. Paul was willing to suffer and die so that Gentiles – those who did not know Christ, those who were separated from Christ – would come to know Him and would be saved and would experience God's saving work. So, this was no light thing to share the riches of Christ. Paul was willing to give his life for it.
4. Paul's Testimony about the Necessity for Gospel Preaching
A very important verse in this regard is Romans 10:14 where Paul says: How then will they – how will anyone – call on Him in whom they will not have believed. Paul has just said in the previous verse that everyone who calls on the name of the Lord will be saved. But how do you call on the name of the Lord, he says in Romans 10:14, unless you believe? You only call on someone in whom you believe. And how are they to believe in Him of whom they have never heard? They will not believe in Christ if they have not heard of Him. That is why it is absolutely essential to preach the gospel. Those who are saved are only those who believe. And those who believe are only those who have heard. And how can someone hear? Well, Paul says, they can only hear with someone preaching. How are they to hear without someone preaching? If there is not preaching, they do not hear. The message must be proclaimed through a preacher. And how are they to preach unless they are sent? Unless someone goes and preaches they will not hear. And they can only believe if they hear. And they will only call if they believe.
And so it is so important, isn't it, to hear the gospel? Paul says, so faith comes from, what? Hearing. Faith comes from hearing the gospel, and hearing through the word about Christ – the word of the gospel. So, the preaching of the gospel is absolutely crucial and fundamental because, if the Gentiles have not heard this word, they are not saved. They are outside of God's purposes.
We read in Romans 1 that the wrath of God is poured out on the Gentiles who have seen the revelation of God through nature. They have seen God as powerful and they see that He is glorious and that He is God. But they have rejected that revelation. They have turned away from God and worshipped idols. They have worshipped the creature rather than the Creator. They have worshipped stone and wood and statues and images and animals and the sun and the moon, rather than worshipping God in Christ. So they are without excuse. Paul does not give any indication, does he, that the revelation that comes through nature saves? The only thing that saves is the gospel and trusting in Christ and believing in Christ and resting in Christ and knowing Christ. And therefore that is why it is so important that the gospel of Christ is proclaimed, because without it the Gentiles are apart from Christ and separate from God's saving promises. And therefore it is very crucial, isn't it, to preach the gospel to those who have not heard it, just as the Apostle Paul did, because faith comes from hearing. And just as Paul did that in his day, so we do today. We proclaim the good news, so that faith can come through hearing the good news of the gospel of Jesus Christ.
So, this is a mystery, Paul says in Ephesians 3:6 and Colossians 1:27, that was not revealed in the Old Testament. A mystery is something that was previously secret, but has now been revealed. It is something that was previously hidden, but is now made known. That mystery is that Jews and Gentiles are now united in Christ through the gospel. That mystery is that when Gentiles believe, they are part of the people of God. They are part of what God is doing in Christ. So now there is not a separation between Jews and Gentiles. But Gentiles who believe the gospel and trust in it are saved and united with the Jews in one people of God. So that is a part of Paul's ministry as well as to bring this good news to the Gentiles of unity in Christ. So, Paul's desire is to bring this gospel to the ends of the earth, from Jerusalem to Illyricum to Spain – wherever Paul can go. If one must hear the gospel of Jesus Christ to be saved, if only the gospel saves and nothing else, then Paul is very passionate about bringing this gospel to the ends of the earth.
5. Paul's Summons to Pray for Mission
And he summons people to pray for his mission. 2 Thessalonians 3:1 – "Pray that the word of the Lord would run and be glorified." In Colossians 4:2-3 – "Pray for him to have wisdom to spread the message in boldness." And, of course, that is still true today. We pray that the message of the word would be spread. The way the gospel is hindered is if that word is not proclaimed to all peoples in all segments. So one of the ways Satan works today is by hindering the preaching and spreading of the gospel to all peoples. So we are to pray that the word would be unleashed, because the power is in the word of the gospel. And when that word is spoken, that word has power. It is the word of the cross that we already saw in 1 Corinthians 2.
Remember, faith comes from hearing the word of the gospel. We saw that in Romans 10:17 or in Galatians 3:2. The Galatians receive the Spirit by hearing the message of the gospel with faith. So, how do people receive the Spirit? It is by hearing the message that message goes forth. So, Paul as a missionary would plant churches wherever he went. We see that in 1 Corinthians 3. He would lay a foundation, as he says. That foundation is Christ and Him crucified. He would give birth, so to speak (1 Cor.4:15), to a new congregation. He would betroth them.
6. Paul's Call to Persevere
And he would emphasize that those new converts not only need to believe initially, but they need to persevere (1 Thess.3:1-10). Paul knows that they are really Christians – that they really received the gospel, that they truly believe – when persecution came and they stood in it. That is why he calls on people again and again to stand in the Lord. Philippians 4:1 – to hold fast the word. If we do not hold fast the word, Paul says, my work is in vain. They need to continue to believe. Paul can summarize his mission in Romans 1:5 and Romans 16:26 as "the obedience of faith". It is not just the initial call to believe, but it is the continuing to believe that is the evidence that we have truly believed. He calls on the believers in Philippians 1:27 to "live worthily of the gospel". Or in 1 Corinthians 15 he calls them to stay true to the gospel to the end, so that they do not fall short of the power of the gospel of Christ – so that they keep believing the message they first embraced.
Paul emphasizes that the power is in the gospel (Rom.1:16). He is not ashamed of the gospel for it is the power of God resulting in salvation to everyone who believes. He points out that the gospel bears fruit and increases wherever it goes (Col.1:6). We saw this just a moment ago, didn't we? The power is in the word. Satan wants the word not to go forth. So we are to pray that the word would run and be glorified, because the gospel has an inherent power. Wherever it goes, it bears fruit and increases. Hence Paul's great desire to see the gospel spread.
And, of course, Paul has other people who work with him, like Euodias and Syntyche, two women who spread the gospel (Phil.4:2-3), probably especially amongst women. There are other evangelists.
And, of course, the gospel is attractive to people when there is moral excellence in the lives of believers as well. When believers live as the children of light, we see in Ephesians 5:7 and following, that commends the gospel to others. When people live in a wise and godly way with outsiders, they commend the gospel to them. The gospel is shown to be beautiful and lovely when believers live in a way that is pleasing to God. We see that as well in Titus 2:1-10. When believers live out their lives in a godly way that is pleasing to God, then unbelievers take notice and they are attracted to the gospel of Christ.
We need to remember what we started with today. And that is the gospel is to be proclaimed for the glory of God and Christ. We see that in Romans 1:5, don't we? It is the glory of Christ that is the purpose of the gospel. We are to bring about the obedience of faith for the sake of His name among all the nations. We do this for the sake of His name – for the honor and glory of Jesus' name. We do this, as Romans 16:25-27 says, to bring glory to the only wise God. The gospel is spread to bring glory to Him.
We see in Philippians 2 that, at the name of Jesus, every knee will bow in heaven and on earth and under the earth and every tongue confess that Jesus Christ is Lord to the glory of God the Father. That is what animates our mission: bringing glory to God and seeing God honored and praised. And that is why Paul is willing to suffer. That is why he is willing to endure such difficulty. It is for the comfort and strength of believers. It is for the salvation of others. The treasure of the gospel is in earthen vessels because it commends the glory of Christ. The sufferings of Paul's ministry show that the strength is in Christ, as we see in 2 Corinthians 12:7-10. Christ is strong and Paul is weak. That shows that Christ is glorious.
Paul as a minister, is a prisoner for the sake of the Gentiles. He does it for their glory. He endures all his suffering (2 Tim.2:10) for the sake of the elect. In Colossians 1, he fills up Christ's afflictions to fulfill the word of God – to advance the gospel so that God would be glorified in all things. So that is the heartbeat of Paul's theology. It is the glory of God in Christ. It is God being magnified in Christ and honored in Christ and praised in Christ. And that is why Paul engages in ministry, so others will know Christ and love Him and serve Him and follow Him forever.