76 If it is supposed that God could not enjoin warfare, because in after times it was said by the Lord Jesus Christ, "I say unto you, That ye resist not evil: but if any one strike you on the right cheek, turn to him the left also," the answer is, that what is here required is not a bodily action, but an inward disposition. The sacred seat of virtue is the heart, and such were the hearts of our fathers, the righteous men of old. But order required such a regulation of events, and such a distinction of times, as to show first of all that even earthly blessings (for so temporal kingdoms and victory over enemies are considered to be, and these are the things which the community of the ungodly all over the world are continually begging from idols and devils) are entirely under the control and at the disposal of the one true God.
Thus, under the Old Testament, the secret of the kingdom of heaven, which was to be disclosed in due time, was veiled, and so far obscured, in the disguise of earthly promises. But when the fullness of time came for the revelation of the New Testament, which was hidden under the types of the Old, clear testimony was to be borne to the truth, that there is another life for which this life ought to be disregarded, and another kingdom for which the opposition of all earthly kingdoms should be patiently borne.
Thus the name martyrs, which means witnesses, was given to those who, by the will of God, bore this testimony, by their confessions, their sufferings, and their death. The number of such witnesses is so great, that if it pleased Christ— who called Saul by a voice from heaven, and having changed him from a wolf to a sheep, sent him into the midst of wolves— to unite them all in one army, and to give them success in battle, as He gave to the Hebrews, what nation could withstand them?
What kingdom would remain unsubdued? But as the doctrine of the New Testament is, that we must serve God not for temporal happiness in this life, but for eternal felicity hereafter, this truth was most strikingly confirmed by the patient endurance of what is commonly called adversity for the sake of that felicity. So in fullness of time the Son of God, made of a woman, made under the law, that He might redeem them that were under the law, made of the seed of David according to the flesh sends His disciples as sheep into the midst of wolves, and bids them not fear those that can kill the body, but cannot kill the soul, and promises that even the body will be entirely restored, so that not a hair shall be lost. Peter's sword He orders back into its sheath, restoring as it was before the ear of His enemy that had been cut off.
He says that He could obtain legions of angels to destroy His enemies, but that He must drink the cup which His Father's will had given Him. He sets the example of drinking this cup, then hands it to His followers, manifesting thus, both in word and deed, the grace of patience. Therefore God raised Him from the dead, and has given Him a name which is above every name; that in the name of Jesus every knee should bow, of things in heaven and of things in earth, and of things under the earth; and that every tongue should confess that Jesus is Lord, to the glory of God the Father. The patriarchs and prophets, then, have a kingdom in this world, to show that these kingdoms, too, are given and taken away by God: the apostles and martyrs had no kingdom here, to show the superior desirableness of the kingdom of heaven.
The prophets, however, could even in those times die for the truth, as the Lord Himself says, "From the blood of Abel to the blood of Zacharia; and in these days, since the commencement of the fulfillment of what is prophesied in the psalm of Christ, under the figure of Solomon, which means the peacemaker, as Christ is our peace, "All kings of the earth shall bow to Him, all nations shall serve Him," we have seen Christian emperors, who have put all their confidence in Christ, gaining splendid victories over ungodly enemies, whose hope was in the rites of idolatry and devil-worship.
There are public and undeniable proofs of the fact, that on one side the prognostications of devils were found to be fallacious, and on the other, the predictions of saints were a means of support; and we have now writings in which those facts are recorded.
Source: Reply to Faustus the Manichaean (New Advent)