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Justin never ended his quest for religious truth even when he converted to Christianity after years of studying various pagan philosophies.And much more here.
As a young man, he was principally attracted to the school of Plato. However, he found that the Christian religion answered the great questions about life and existence better than the philosophers.
Upon his conversion he continued to wear the philosopher's mantle, and became the first Christian philosopher. He combined the Christian religion with the best elements in Greek philosophy. In his view, philosophy was a pedagogue of Christ, an educator that was to lead one to Christ.
Justin is known as an apologist, one who defends in writing the Christian religion against the attacks and misunderstandings of the pagans. Two of his so-called apologies have come down to us; they are addressed to the Roman emperor and to the Senate.
For his staunch adherence to the Christian religion, Justin was beheaded in Rome in 165.