One God, Three Equal Persons
WHEN did these come into being? They are above all "When." But, if I am to speak with something more of boldness,--when the Father did. And when did the Father come into being. There never was a time when He was not. And the same thing is true of the Son and the Holy Ghost. Ask me again, and again I will answer you, When was the Son begotten? When the Father was not begotten. And when did the Holy Ghost proceed? When the Son was, not proceeding but, begotten--beyond the sphere of time, and above the grasp of reason; although we cannot set forth that which is above time, if we avoid as we desire any expression which conveys the idea of time (Theological Orations III.3).
TO us there is One God, for the Godhead is One, and all that proceedeth from Him is referred to One, though we believe in Three Persons. For one is not more and another less God; nor is One before and another after; nor are They divided in will or parted in power; nor can you find here any of the qualities of divisible things; but the Godhead is, to speak concisely, undivided in separate Persons; and there is one mingling of Light, as it were of three suns joined to each other. When then we look at the Godhead, or the First Cause, or the Monarchia, that which we conceive is One; but when we look at the Persons in Whom the Godhead dwells, and at Those Who timelessly and with equal glory have their Being [in] the First Cause--there are Three Whom we worship (Theological Orations V.14).
THIS, then, is my position with regard to these things, and I hope it may be always my position, and that of whosoever is dear to me; to worship God the Father, God the Son, and God the Holy Ghost, Three Persons, One Godhead, undivided in honour and glory and substance and kingdom (Theological Orations V.28).