And now, if the whole of perfection consisted only in work and not also in faith, and if at the day of judgment not what a man had believed but only what he had done were sought, who would be of such arrogance that, neglecting the authority of ecclesiastical doctrine, he would flatter himself on his own righteousness? Since not only, according to the Apostle (II Thess. 3:9; I Pet. 5:3), ought we to provide a pattern for the faithful, but we must also instruct those very faithful who have been divinely committed to us to be formed: concerning the Father, how he alone is taken to be unbegotten; concerning the Son, how he is begotten from him; concerning the Holy Spirit, how, proceeding from the Father and the Son, he can be called neither unbegotten nor begotten;
how these three are one, and how this one is not divided but distinguished into three: how neither the Father nor the Holy Spirit, but the Son alone, ineffably born of the Father alone, took upon himself the whole man without any change of his own substance; and proved himself true God and man through his miracles and his sufferings, allowed himself to be apprehended, willed to be slain, rose again on the third day, by his own power raised into heaven the man assumed from us, and by the example of his own resurrection granted to us, regenerated in him, the hope of happily rising; made us his members; threatened punishment to those not believing in him or departing from him, and promised the heavenly kingdom to those cleaving to him.