Clement of Alexandria is an important but often overlooked theologian of the late second and early third century. His student, Origen, is better known.
Like Origen, Clement himself has been a somewhat controversial figure in the eyes of later theologians. He is well received by the Coptic church, was declared a heretic a millennium or so after he lived by the Eastern Orthodox, was considered a saint by the Roman church until shortly after the Reformation when this honor was rescinded by the Pope, and has been popular among early Protestants due to his clear articulation of the doctrine that every point of doctrine must be proven from scripture if it is to be accepted as true.
Clement’s formulation of the doctrine that the one God of the Christian faith is the person of the Father does not differ from that of other theologians of the same era who articulated this first article of the Christian faith against various pseudo-gnostic heretics, such as Irenaeus. We see his belief stated explicitly in the following quote:
“Wherefore also the apostle designates as “the express image (χαρακτῆρα) of the glory of the Father” the Son, who taught the truth respecting God, and expressed the fact that the Almighty is the one and only God and Father, “whom no man knoweth but the Son, and he to whom the Son shall reveal Him. That God is one is intimated by those “who seek the face of the God of Jacob;” whom being the only God, our Saviour and God characterizes as the Good Father.” (Stromata, Book 7, Chapter X.)
Of special interest is this next quote, included by Clement in his Stromata from the now lost source The Preaching of Peter, from which we see Peter explicitly teach that the one God of the Christian faith is the person of the Father:
“And that the men of highest repute among the Greeks knew God, not by positive knowledge, but by indirect expression, Peter says in the Preaching: “Know then that there is one God, who made the beginning of all things, and holds the power of the end; and is the Invisible, who sees all things; incapable of being contained, who contains all things; needing nothing, whom all things need, and by whom they are; incomprehensible, everlasting, unmade, who made all things by the ‘Word of His power,’ that is, according to the gnostic scripture, His Son.”” (Stromata Book 6, Chapter V)