The Christian Researh Institute has an excellent article here on the second century apologist, Athenagoras of Athens.

“Athenagoras of Athens is one of three great Greek pagan philosophers who, during the second century AD, converted to Christianity on account of the wisdom of its teachings and the moral lives of its followers. Rather than abandon their former training, Aristides, Justin Martyr, and Athenagoras all used their pagan learning as a springboard for bearing witness to the gospel before the most powerful rulers of their day.“