According to this truth and this Word of God, we believe in one only God,1 who is one single essence, in which are three persons, really, truly, and eternally distinct according to their incommunicable properties; namely, the Father, the Son, and the Holy Spirit.2 The Father is the cause, origin, and beginning of all things visible and invisible.3 The Son is the Word, the wisdom, and the image of the Father.4 The Holy Spirit is the eternal power and might who proceeds from the Father and the Son.5 Nevertheless, God is not by this distinction divided into three, since the Holy Scriptures teach us that the Father, the Son, and the Holy Spirit each has His personal existence, distinguished by Their properties; but in such a way that these three persons are but one only God.
It is therefore evident that the Father is not the Son, nor the Son the Father, and likewise the Holy Spirit is neither the Father nor the Son. Nevertheless, these persons thus distinguished are not divided, nor intermixed; for the Father has not assumed our flesh and blood, neither has the Holy Spirit, but the Son only. The Father has never been without His Son,6 or without His Holy Spirit. For these three, in one and the same essence, are equal in eternity. There is neither first nor last; for They are all three one, in truth, in power, in goodness, and in mercy.
1 1 Cor 8:4-6
2Mt 3:16-17; Mt 28:19
4Prov 8:22-31; Jn 1:14, 5:17-26; 1 Cor 1:24; Col 1:15- 20; Heb 1:3; Rev 19:13
6Mic 5:2; Jn 1:1-2