See Pastoral Epistles.
TITUS or TITIUS JUSTUS
(Titos or Titios Ioustos (Ac 18:7)): Titus or Titius--for the manuscripts vary in regard to the spelling--was the prenomen of a certain Corinthian, a Jewish proselyte (sebomenos ton Theon). See Proselyte). His name seems also to indicate that he was a Roman by birth. He is altogether a different person from Titus, Paul’s assistant and companion in some of his journeys, to whom also the Epistle to Titus is addressed.
Titus or Titius Justus was not the "host of Paul at Corinth" (HDB, article "Justus," p. 511), for Luke has already narrated that, when Paul came to Corinth, "he abode with" Aquila and Priscilla (Ac 18:3). What is said of Titius Justus is that when the Jews in Corinth opposed themselves to Paul and blasphemed when he testified that Jesus was the Christ, then Paul ceased to preach the gospel in the Jewish synagogue as he had formerly done, and "he departed thence, and went into the house of a certain man named Titus Justus, one that worshipped God, whose house joined hard to the synagogue" (Ac 18:7).
"Titius Justus was evidently a Roman or a Latin, one of the coloni of the colony Corinth. Like the centurion Cornelius, he had been attracted to the synagogue. His citizenship would afford Paul an opening to the more educated class of the Corinthian population" (Ramsay, Paul the Traveler and the Ro Citizen, 256).
Paul’s residence in Corinth continued for a year and a half, followed without a break by another period indicated in the words, he "tarried after this yet many days" (Ac 18:11,18), and during the whole of this time he evidently used the house of Titius Justus, for the purposes both of preaching the gospel and of gathering the church together for Christian worship and instruction, "teaching the word of God among them" (Ac 18:11).
Titius Justus, therefore, must have been a wealthy man, since he possessed a house in which there was an apartment sufficiently large to be used for both of these purposes; and he himself must have been a most enthusiastic member of the church, when in a period of protracted difficulty and persecution, he welcomed Paul to his house, that he might use it as the meeting-place of the church in Corinth.
See Justus, (2).