I have also written:
In the book Gods and the one God, Robert Grant writes that Athenagoras constructed his theological concepts from Platonic and Aristotelian philosophy (Athenagoras also incorporated Stoic thought when systematizing the nature of God). Grant provides compelling evidence that Athenagoras' ideas are Trinitarian concepts in utero that simultaneously employ Platonic and Pythagorean philosophical notions to explain Christian theology (Grant 158).
An example of Athenagoras' Platonic tendencies is witnessed from this passage:
But the Son of God is the Logos of the Father, in idea and in operation; for after the pattern of Him and by Him "Or, by Him and through Him" were all things made, the Father and the Son being one. And, the Son being in the Father and the Father in the Son, in oneness and power of spirit, the understanding and reason (νοῦς καὶ λόγος) of the Father is the Son of God. But if, in your surpassing intelligence, it occurs to you to inquire what is meant by the Son, I will state briefly that He is the first product of the Father, not as having been brought into existence (for from the beginning, God, who is the eternal mind [νοῦς], had the Logos in Himself, being from eternity instinct with Logos [λογικός]); but inasmuch as He came forth to be the idea and energizing power of all material things, which lay like a nature without attributes, and an inactive earth, the grosser particles being mixed up with the lighter. The prophetic Spirit also agrees with our statements. "The Lord," it says, "made me, the beginning of His ways to His works" (A Plea for Christians).
Athenagoras seems to believe that the Logos of God gives form to matter which lacks attributes. He applies Proverbs 8:22 to this activity of the Logos as the Reason of God. The Logos appears to provide intelligibility to the world. At most, what Athenagoras writes can be interpreted as a precursor to Trinitarianism.