23 Let Sabellius, if he dare, confound Father and Son as two names with one meaning, making of them not Unity but One Person. He shall have a prompt answer from the Gospels, not once or twice, but often repeated, This is My beloved Son, in Whom I am well pleased. He shall hear the words, The Father is greater than I, and I go to the Father, and Father, I thank You, and Glorify Me, Father, and You are the Son of the living God. Let Hebion try to sap the faith, who allows the Son of God no life before the Virgin's womb, and sees in Him the Word only after His life as flesh had begun.
We will bid him read again, Father, glorify Me with Your own Self with that glory which I had with You before the world was, and In the beginning was the Word, and the Word was with God, and the Word was God, and All things were made through Him, and He was in the world, and the world was made through Him, and the world knew Him not. Let the preachers whose apostleship is of the newest fashion— an apostleship of Antichrist— come forward and pour their mockery and insult upon the Son of God.
They must hear, I came out from the Father and The Son in the Father's bosom, and I and the Father are One, and I in the Father, and the Father in Me. And lastly, if they be wrath, as the Jews were, that Christ should claim God for His own Father, making Himself equal with God, they must take the answer which He gave the Jews, Believe My works, that the Father is in Me and I in the Father. Thus our one immovable foundation, our one blissful rock of faith, is the confession from Peter's mouth, You are the Son of the living God. On it we can base an answer to every objection with which perverted ingenuity or embittered treachery may assail the truth.
Source: On the Trinity (New Advent)