The answer
The Divine Hypostases-the Father, the Son, and the Holy Spirit-are not parts or pieces that form the Divine Being, God forbid, for the Divine Being is one, unbroken and undivided. The Father is not a part of God, but God Himself is the Father (an Eastern word8 denoting “originator”). “God is the originator of existence,” and that is why we call Him “the Father.”
The Holy Spirit is not a part of God, God forbid, but God is the Greatest Spirit, the Holy One, the Framer of life, its Forger, and its Author.
The Son is not a part of God, but He Is His Word and rational uttering.
God, being the Greatest Mind and the Fashioner of existence, was incarnate in Christ. Christ, then, is the Word, or the Rational Uttering of God, or the Reasonable Mind of God. He is the Son of God, that is to say that He is the “Greatest Manifestation of God,” i.e. the appearance of God in Christ.
The Divine Hypostases, then, are God Himself, upon Them the Divine Essence stands, and without Them the Divine Essence has no being or existence.
God cannot be without His Being (the Father), rational without His Mind (the Son), or living without His Spirit (the Holy Spirit). God cannot be divided, and His attributes cannot be split. God, for example, is merciful and just. It is difficult to speak of the justice of God alone, or the mercy of God alone. Yet, I say that God is just in His mercy, or that His mercy is just, or that He is merciful in His justice, or that His justice is merciful, or that the mercy of God is full of justice, or that the justice of God is full of mercy.
His Holiness Pope Tawadros II
Notes
8 Translator’s note: The word referred to here is ‘ab.
Pope Tawadros II, My Faith: A Series of Dialogues on the Creed (Coptic Orthodox Patriarchate, 2014), 27–28.

