Justin the Martyr, one of the earliest writers in the second century, considers war as unlawful. He makes also the devil "the author of all war." No severer sentence could have been passed upon it than this, when we consider it as coming from the lips of an early Christian. The sentiment too was contrary to the prevailing sentiments of the times, when, of all professions, that of war was most honourable, and was the only one that was considered to lead to glory. It resulted, therefore, in all probablity, from the new views, which Justin had acquired by a perusal of such of the scriptures, as had then fallen into his hands.
Tatian, who was the disciple of Justin, in his oration to the Greeks, speaks precisely in the same terms on the same subject.
From the different expressions of Clemens of Alexandria, a contemporary of the latter, we collect his opinion to be decisive against the lawfulness of war.
Tertullian, who may be mentioned next in order of time, strongly condemned the practice of bearing arms, as it related to Christians. I shall give one or two extracts from him on this subject. In his dissertation on the worship of idols, he says, "Though the soldiers came to John, and received a certain form to be observed, and though the centurion believed, yet Jesus Christ, by disarming Peter, disarmed every soldier afterwards: for custom never sanctions an illicit act." And in his "Soldier's Garland," he says, "Can a soldier's life be lawful, when Christ has pronounced, that he who lives by the sword shall perish by the sword? Can one, who professes the peaceable doctrines of the Gospel, be a soldier, when it is his duty not so much as to go to law? and shall he, who is not to revenge his own wrongs, be instrumental in bringing others into chains, imprisonment, torment, death?"
Cyprian, in his Epistle to Donatus, takes a view of such customs in his own times, as he conceived to be repugnant to the spirit or the letter of the Gospel. In looking at war, which was one of them, he speaks thus: "Suppose thyself, says he, with me on the top of some very exalted eminence, and from thence looking down upon the appearances of things beneath thee. Let our prospect take in the whole horizon, and let us view, with the indifference of persons not concerned in them, the various motions and agitations of human life. Thou wilt then, I dare say, have a real compassion for the circumstances of mankind, and for the posture in which this view will represent them. And when thou reflectest upon thy condition, thy thoughts will rise in transports of gratitude and praise to God for having made thy escape from the pollutions of the world. The things thou wilt principally observe, will be the highways beset with robbers, the seas with pirates, encampments, marches, and all the terrible forms of war and, bloodshed. When a single murder is committed, it shall be deemed perhaps a crime; but that crime shall commence a virtue, when committed under the shelter of public authority, so that punishment is not rated by the measure of guilt, but the more enormous the size of the wickedness is, so much the greater is the chance for impunity." These are the sentiments of Cyprian, and that they were the result of his views of Christianity, as taken from the divine writings, there can be little doubt. If he had stood upon the same eminence, and beheld the same sights previously to his conversion, he might, like others, have neither thought piracy dishonourable, nor war inglorious.
Lactantius, who lived some time after Cyprian, in his treatise "Concerning the True Worship of God," says, "It can never be lawful for a righteous man to go to war, whose warfare is in righteousness itself," And in another part of the same treatise he observes, that "no exception can be made with respect to this command of God. It can never be lawful to kill a man, whose person the Divine Being designed to be sacred as to violence."
It will be unnecessary to make extracts from other of the early Christian writers, who mention this subject. I shall therefore only observe, that the names of Origen, Archelaus, Ambrose, Chrysostom, Jerom, and Cyril, may be added, to those already mentioned, as the names of persons who gave it as their opinion, that it was unlawful for Christians to go to war.
With respect to the practice of the early Christians, which is the next point to be considered, it may be observed, that there is no well authenticated instance upon record, of Christians entering into the army for the first two centuries; but it is true, on the other hand, that they declined the military profession, as one in which it was not lawful for them to engage.
The first species of evidence, which I shall produce to this point, may be found in the following facts, which reach from the year 169 to the year 198, Avidius Crassus had rebelled against the emperor Verus, and was slain in a short time afterwards. Clodius Albinus in one part of the world, and Pescenninus Niger in another, rebelled against the emperor Severus, and both were slain likewise. Now suspicion fell, as it always did in these times, if any thing went wrong, upon the Christians, as having been concerned upon these occasions. But Tertullian, in his Discourse to Scapula, tells us, that no Christians were to be found in these armies. And yet these armies were extensive. Crassus was master of all Syria, with its four legions, Niger of the Asiatic and Egyptian legions, and Albinus of those of Britain, which legions together contained between a third and an half of the standing legions of Rome. And the fact, that no Christians were to be found in these, is the more remarkable, because, according to the same Tertullian, Christianity had reached all the places, in which these armies were.
A second species of evidence, as far as it goes, may be collected from expressions and declarations in the works of certain authors of those times. Justin the Martyr, and Tatian, make distinctions between soldiers and Christians; and the latter says, that the Christians declined even military commands. Clemens of Alexandria, gives the Christians, who were cotemporary with him, the appellation of "peaceable, or of the followers of peace," thus distinguishing them from the soldiers of his age. And he says expressly, that "those, who were the followers of peace, used none of the instruments of war."