34 Flee from such men as much as you can; avoid with a wholesome caution those who adhere to their mischievous contact. Their word does eat as does a cancer; their conversation advances like a contagion; their noxious and envenomed persuasion kills worse than persecution itself. In such a case there remains only penitence which can make atonement. But they who take away repentance for a crime, close the way of atonement. Thus it happens that, while by the rashness of some a false safety is either promised or trusted, the hope of true safety is taken away.
Source: The Treatises of Cyprian (New Advent)