17 But if there are some who think that they can return to the Church not with prayers but with threats, or suppose that they can make a way for themselves, not with lamentation and atonements, but with terrors, let them take it for certain that against such the Church of the Lord stands closed; nor does the camp of Christ, unconquered and firm with the Lord's protection, yield to threats. The priest of God holding fast the Gospel and keeping Christ's precepts may be slain; he cannot be conquered.
Zacharias, God's priest, suggests and furnishes to us examples of courage and faith, who, when he could not be terrified with threats and stoning, was slain in the temple of God, at the same time crying out and saying, what we also cry out and say against the heretics, “Thus says the Lord, You have forsaken the ways of the Lord, and the Lord will forsake you.” For because a few rash and wicked men forsake the heavenly and wholesome ways of the Lord, and not doing holy things are deserted by the Holy Spirit, we also ought not therefore to be unmindful of the divine tradition, so as to think that the crimes of madmen are greater than the judgments of priests; or conceive that human endeavours can do more to attack, than divine protection avails to defend.
Source: The Epistles of Cyprian (New Advent)