Titus Justus (Titou Ioustou). So Aleph E Vulgate, while B has Titiau Ioustou, while most MSS. have only Ioustou. Evidently a Roman citizen and not Titus, brother of Luke, of Galatians 2:1 . We had Barsabbas Justus ( Acts 1:23 ) and Paul speaks of Jesus Justus ( 4:11 ). The Titii were a famous family of potters in Corinth. This Roman was a God-fearer whose house "joined hard to the synagogue" (hn sunomorousa th sunagwgh). Periphrastic imperfect active of sunomorew, a late (Byzantine) word, here only in the N.T., followed by the associative instrumental case, from sunomoro (sun, omoro from omo, joint, and oro, boundary) having joint boundaries, right next to. Whether Paul chose this location for his work because it was next to the synagogue, we do not know, but it caught the attendants at the synagogue worship. In Ephesus when Paul had to leave the synagogue he went to the school house of Tyrannus ( 19:9 ). The lines are being drawn between the Christians and the Jews, drawn by the Jews themselves.