Cyprian of Carthage, On the Unity of the Church 1

The Lord warns us: "You are the salt of the earth" (Matt. 5:13). He commands us to be innocent as doves, yet prudent as serpents. What else, dearest brothers, should we do but look ahead and stay alert, with anxious hearts, so that we both grasp and guard against the snares of our cunning enemy? We have put on Christ, the wisdom of God the Father; we must not appear less wise in protecting our salvation. Persecution is not the only danger, nor only those open attacks that rage against God's servants to overthrow and cast them down. Caution comes easily when the threat is obvious, and the mind readies itself for battle when the adversary shows himself. The enemy is far more to be feared and avoided when he creeps up secretly, deceiving under the guise of peace and slipping in by hidden approaches—that is why he is called the serpent. Such is his constant cunning, the blind and hidden deceit he uses to entrap human beings. From the very beginning of the world he deceived, coaxing inexperienced souls with lying words and catching them in their unguarded credulity. He even attempted to tempt the Lord Himself, stealing in again as if to deceive once more. Yet he was recognized and repulsed, and so he was thrown down, because he was identified and exposed.