The answer
The order of “First, Second, and Third” is related to humanity’s knowledge of God. They knew God as Father before they knew Him as Son, and that is because the Incarnation took place later in time.
What we say of the Master Christ, the Second Hypostasis, we say of the Holy Spirit, the Third Hypostasis.
His Holiness Pope Tawadros II
Pope Tawadros II, My Faith: A Series of Dialogues on the Creed (Coptic Orthodox Patriarchate, 2014), 46.
