Thereafter he expounds the appellation of Son, and of product of generation, and very many varieties of sons, of God, of men, of rams, of perdition, of light, and of day
But our discourse has diverged too far from the subject before us, in following out the questions which arise from time to time by way of inference. Let us therefore once more resume its sequence, as I imagine that the phrase under examination has been sufficiently shown, by what we have said, to be contradictory not only to the truth, but also to itself. For if, according to their view, the natural relation to the Father is established by the appellation of “the Son,” and so with that of the “product of generation” to Him Who has begotten Him (as these men's wisdom falsely models the terms significant of the Divine nature into a verbal arrangement, according to some grammatical frivolity), no one could longer doubt that the mutual relation of the names which is established by nature is a proof of their kindred, or rather of their identity of essence. But let not our discourse merely turn about our adversaries' words, that the orthodox doctrine may not seem to gain the victory only by the weakness of those who fight against it, but appear to have an abundant supply of strength in itself. Let the adverse argument, therefore, be strengthened as much as may be by us ourselves with more energetic advocacy, that the superiority of our force may be recognized with full confidence, as we bring to the unerring test of truth those arguments also which our adversaries have omitted. He who contends on behalf of our adversaries will perhaps say that the name of “Son,” or “product of generation,” does not by any means establish the fact of kindred in nature. For in Scripture the term “child of wrath” is used, and “son of perdition,” and “product of a viper;” and in such names surely no community of nature is apparent. For Judas, who is called “the son of perdition,” is not in his substance the same with perdition, according to what we understand by the word. For the signification of the “man” in Judas is one thing, and that of “perdition” is another. And the argument may be established equally from an opposite instance. For those who are called in a certain sense “children of light,” and “children of the day,” are not the same with light and day in respect of the definition of their nature, and the stones are made Abraham's children when they claim their kindred with him by faith and works; and those who are “led by the Spirit of God,” as the Apostle says, are called “Sons of God,” without being the same with God in respect of nature; and one may collect many such instances from the inspired Scripture, by means of which deceit, like some image decked with the testimonies of Scripture, masquerades in the likeness of truth.
Well, what do we say to this? The divine Scripture knows how to use the word “Son” in both senses, so that in some cases such an appellation is derived from nature, in others it is adventitious and artificial. For when it speaks of “sons of men,” or “sons of rams,” it marks the essential relation of that which is begotten to that from which it has its being: but when it speaks of “sons of power,” or “children of God,” it presents to us that kinship which is the result of choice. And, moreover, in the opposite sense, too, the same persons are called “sons of Eli,” and “sons of Belial,” the appellation of “sons” being easily adapted to either idea. For when they are called “sons of Eli,” they are declared to have natural relationship to him, but in being called “sons of Belial,” they are reproved for the wickedness of their choice, as no longer emulating their father in their life, but addicting their own purpose to sin. In the case, then, of this lower nature of ours, and of the things with which we are concerned, by reason of human nature being equally inclined to either side (I mean, to vice and to virtue), it is in our power to become sons either of night or of day, while our nature yet remains, so far as the chief part of it is concerned, within its proper limits. For neither is he who by sin becomes a child of wrath alienated from his human generation, nor does he who by choice addicts himself to good reject his human origin by the refinement of his habits, but, while their nature in each case remains the same, the differences of their purpose assume the names of their relationship, according as they become either children of God by virtue, or of the opposite by vice.
Source: Against Eunomius (New Advent)