The Epistles of Ignatius

Flee, therefore, those evil offshoots [of Satan], which produce death-bearing fruit, whereof if any one tastes, he instantly dies. For these men are not the planting of the Father. For if they were, they would appear as branches of the cross, and their fruit would be incorruptible. By it He calls you through His passion, as being His members. The head, therefore, cannot be born by itself, without its members; God, who is [the Saviour] Himself, having promised their union.