42 To believe, therefore, that Jesus Christ is the Son of God is true salvation, is the acceptable service of an unfeigned faith. For we have no love within us towards God the Father except through faith in the Son. Let us hear Him speaking to us in the words of the Epistle;— Every one that loves the Father loves Him that is born from Him. What, I ask, is the meaning of being born from Him? Can it mean, perchance, being created by Him? Does the Evangelist lie in saying that He was born from God, while the heretic more correctly teaches that He was created?
Let us all listen to the true character of this teacher of heresy. It is written, He is antichrist, that denies the Father and the Son. What will you do now, champion of the creature, conjurer up of a novel Christ out of nothing? Hear the title which awaits you, if you persist in your assertion. Or do you think that perhaps you may still describe the Father and the Son as Creator and Creature, and yet by an ingenious ambiguity of language escape being recognised as antichrist?
If your confession embraces a Father in the true sense, and a Son in the true sense, then I am a slanderer, assailing you with a title of infamy which you have not deserved. But if in your confession all Christ's attributes are spurious and nominal, and not His own, then learn from the Apostle the right description of such a faith as yours; and hear what is the true faith which believes in the Son. The words which follow are these— He that denies the Son, the same has not the Father: he that confesses the Son has both the Son and the Father. He that denies the Son is destitute of the Father; he that confesses and has the Son has the Father also. What room is there here for adoptive names? Does not every word tell of the Divine nature? Learn how completely that nature is present.
Source: On the Trinity (New Advent)