“Either they were conquered by the sight of their neighbors’ patient life, or they were convinced by noticing the extraordinary kindness and patience of some defrauded traveling companions, or they were overcome by encountering and testing this attitude in people with whom they had business dealings. Anyone who is not found living in accordance with his teachings should not be regarded as a Christian even if he confesses to Christ’s teaching with his lips.”
(Justin Martyr, ‘Apology #16’)