Article 8: God is One in Essence, Yet Distinguished in Three Persons.
According to this truth and this Word of God, we believe in one only God, who is one single essence,6 in which are three persons, really, truly, and eternally distinct, according to their incommunicable properties; namely, the Father, and the Son, and the Holy Ghost. The Father is the cause, origin, and beginning of all things visible and invisible; the Son is the word, wisdom, and image of the Father; the Holy Ghost is the eternal power and might, proceeding from the Father and the Son. Nevertheless God is not by this distinction divided into three, since the Holy Scriptures teach us that the Father, and the Son, and the Holy Ghost have each His personality, distinguished by their properties; but in such wise that these three persons are but one only God.
Hence then, it is evident that the Father is not the Son, nor the Son the Father, and likewise the Holy Ghost is neither the Father nor the Son. Nevertheless these persons thus distinguished are not divided nor intermixed; for the Father hath not assumed the flesh, nor hath the Holy Ghost, but the Son only. The Father hath never been without His Son, or without His Holy Ghost. For they are all three coeternal and coessential. There is neither first nor last; for they are all three one, in truth, in power, in goodness, and in mercy.