Justin Martyr Walks a Tightrope | Rod Bennett | From "Justin Martyr", in Four Witnesses: The Early Church in Her Own Words | Ignatius Insight
Justin's conversion to Christianity is thought to have happened at the city of Ephesus, around A.D. 130, when our inquisitive young Samaritan was roughly thirty years of age. And though he was undoubtedly given a warm reception into the Christian congregation there in Asia—that venerable church founded by John, written to by Ignatius from the house of Polycarp—Justin, to tell the truth, may have raised a few eyebrows by his conduct as a new believer. For the fact is that he continued to frequent his old haunts. He kept all his old friendships and ran with the same unregenerate crowd he had associated with as a heathen. In short, Justin of Neapolis became known, much like his Lord before him, as "the friend of publicans and sinners"—only in Justin's case, the publicans and sinners were not prostitutes or winebibbers, but mystic Pythagorean mathematicians and long-faced logicians studiously following Xenophon and Parmenides. In other words, Justin became an apologist—a defender of the faith, a philosophical evangelist—and from the day of his redemption he seems to have been possessed by one burning desire: to see his own people, his brother philosophers, come to the knowledge of the truth.
The Dialogue with Trypho, which took place at Ephesus during this period,  gives us a window into Justin's methods. As it opens, we find him, wearing his pallium, walking among the colonnades of a great temple (possibly the same great temple of Diana where earlier Paul had raised the ire of the silversmiths [Acts 19]). Such places were where the philosophers of the day plied their trade, and little groups of them could always be found arguing, from sun up to sun down, on the steps of every pagan shrine in the Empire. On this particular day, Justin drew the attention of Trypho, the Hellenized rabbi, famous as one of the most learned Jews in the East. Yet it might just as well have been the representative of any of a hundred different world views who chose to debate him that day, for they all met here on equal terms, all contending (though they little knew it at the time) for the intellectual fate of Europe and the world.