It doesn’t mean what we mean colloquially where we talk about somebody being an impeccable person. I think of my mother as being that kind of person. She would sit there on the sofa most of the time with a piece of masking tape wrapped around her fingers backwards; that is, the sticky side out. So that any little speck of anything she spotted she could go over and pick up; a hair, a piece of lint. This is my mother — impeccable. This is not what this word means.
This comes from the Latin word to sin (peccare). Impeccability of Christ means that Christ could not have sinned. The impeccability of Christ means that it was impossible for Christ to sin. Shedd in his systematic theology, Dogmatic Theology defines it this way, “an impeccable will is one that is so mighty in its self determination to good, that it cannot be conquered by any temptation to evil however great.” The church has affirmed though the centuries that Christ did not sin. This is affirmed by all Christian people within orthodoxy and there is abundant Scriptural evidence for this.
This is not controversial, but what is controversial is that Christ could not sin. While the first one is true, Christ did not sin, that is not the impeccability doctrine. The impeccability doctrine is that Christ could not sin. It is the standard position that the church has held through the centuries but it is increasingly a minority view today among theologians. Many and perhaps it is at the point where most have given up the impeccability doctrine. There is one fundamental reason why they give it up. It is obvious, is if Christ could not sin, in what sense did he really face temptation, how could temptation be genuine for him as Christian theology has also held, that He really was tempted? The book of Hebrews makes that clear. Let me tell you where I am going with this. I continue to affirm the impeccability doctrine that Christ could not sin. Obviously, if that is the case, I have my work cut out for me and I am going to involve you in that of defending a viable vibrant notion of the real temptations of Christ having also claimed of Him that he could not sin. Both are true, both are required biblically. How they can be held together is a challenge but one that I want to suggest to you.
Christ could not sin. In Latin the way they put this is He was non posse peccare, not able to sin, peccare the term for sin, so impeccability, He could not sin not merely posse non peccare able not to sin. Everyone agrees with that, in fact He did not sin but here is the stronger affirmation.