3 Which sentence dishonors the holy Martyrs, nay rather takes away holy martyrdoms altogether. For they would do more justly and wisely, according to these men, not to confess to their persecutors that they were Christians, and by confessing make them murderers: but rather by telling a lie, and denying what they were, should both themselves keep safe the convenience of the flesh and purpose of the heart, and not allow those to accomplish the wickedness which they had conceived in their mind.
For they were not their neighbors in the Christian faith, that with them it should be their duty to speak the truth in their mouth which they spoke in their heart; but moreover enemies of Truth itself. For if Jehu (whom it seems they do prudently to single out unto themselves to look unto as an example of lying) falsely gave himself out for a servant of Baal, that he might slay Baal's servants: how much more justly, according to their perversity, might, in time of persecution, the servants of Christ falsely give themselves out, for servants of demons, that the servants of demons might not slay servants of Christ; and sacrifice to idols that men might not be killed, if Jehu sacrificed to Baal that he might kill men?
For what harm would it do them, according to the egregious doctrine of these speakers of lies, if they should lyingly pretend a worship of the Devil in the body, when the worship of God was preserved in the heart? But not so have the Martyrs understood the Apostle, the true, the holy Martyrs. They saw and held that which is written, “With the heart man believes unto righteousness, and with the mouth confession is made unto salvation;” and, “In their mouth was found no lie:” and so they departed irreproachable, to that place where to be tempted by liars any further they will not fear; because they will not have liars any more in their heavenly assemblies, either for strangers or neighbors.
As for that Jehu, by an impious lie and a sacrilegious sacrifice making inquisition for impious and sacrilegious men for to kill them, they would not imitate him, no, not though the Scripture had said nothing concerning him, what manner of man he was. But, seeing it is written that he had not his heart right with God; what profited it him, that for some obedience which, concerning the utter destruction of the house of Ahab, he exhibited for the lust of his own domination. he received some amount of transitory wages in a temporal kingdom?
Let, rather, the truth-telling sentence of the Martyrs be yours to defend: to this I exhort you, my brother, that you may be against liars, not a teacher of lying, but an asserter of truth. For, I pray you, attend diligently to what I say, that you may find how needful to be shunned is that which, with laudable zeal indeed towards impious men, that they may be caught and corrected, or avoided, but yet too incautiously, is thought fit to be taught.
Source: To Consentius: Against Lying (New Advent)