Ignatius of Antioch

Every one that teaches anything beyond what is commanded, though he be [deemed] worthy of credit, though he be in the habit of fasting, though he live in continence, though he work miracles, though he have the gift of prophecy, let him be in thy sight as a wolf in sheep's clothing, labouring for the destruction of the sheep. If any one denies the cross, and is ashamed of the passion, let him be to thee as the adversary himself. "Though he gives all his goods to feed the poor, though he remove mountains, though he give his body to be burned," let him be regarded by thee as abominable. If any one makes light of the law or the prophets, which Christ fulfilled at His coming, let him be to thee as antichrist. If any one says that the Lord is a mere man, he is a Jew, a murderer of Christ.