I have taken heed to the words of Truth Himself:- “The Lord thy God is one.” (Deut. 6.4) And “Thou shalt fear the Lord thy God, and shalt serve Him only, and thou shalt not have strange, gods.” (Deut. 6.13) Again, “Thou shalt not make to thyself a graven thing, nor the likeness of anything that is in heaven above, or in the earth beneath” (Ex. 20.4); and “Let them be all confounded that adore graven things.” (Ps. 97.7) Again, “The gods that have not made heaven and earth, let them perish.” (Jer. 10.11) In this way God spoke of old to the patriarchs through the prophets, and lastly, through His only-begotten Son, on whose account He made the ages. He says, “This is eternal life, that they may know Thee, the only true God, and Jesus Christ whom Thou didst send.” (Jn 17.3) I believe in one God, the source of all things, without beginning, uncreated, immortal, everlasting, incomprehensible, bodiless, invisible, uncircumscribed,* without form. I believe in one supersubstantial being, one divine Godhead in three entities, the Father, the Son, and the Holy Ghost, and I adore Him alone with the worship of latreia. I adore one God, one Godhead but three Persons, God the Father, God the Son made flesh, and God the Holy Ghost, one God.
I grew up non-Trinitarian… and it is possible that I have come to adore St. John Damascene not just because of the Trinity, but likewise because of this patron saint status… of academics. The Trinity is the great Mystery, from which all doctrine properly flows. Here, the one who suffered under early Islamic rule, still maintains and safeguards this holy doctrine by placing it into words we must understand.