Some points to clear up about Orthodoxy.
1. God is existentially three, but ontologically one. The Son is, according to a literal translation of the Nicene Creed from Greek, "essentially the same as the Father".
2. Christ is ontologically two (God and man), but existentially one.
3. The Filioque, according to the official explanation of the RCC, means that Father and the Son are the Spirit's joint existential principle. This is based on the Roman assertion that a person's existential principle is an essential quality, and since the Father and Son are ontologically the same, the Spirit must proceed of both; in Orthodoxy, by contrast, existence precedes essence; if the Roman position were true, the Spirit would also proceed of himself, since he is ontologically the Father and the Son.
4. To say the Spirit proceeds through or even from the Son in sense of always operating through him, is perfectly Orthodox (since they are operationally identical), but it is wrong to say the Son and Father are a dual principle of the Spirit, which is how the Filioque is intended. Not surprising, since the Spirit's procession in the Creed was originally about existential principle.
5. The terms "energies" and "synergy" in Orthodox theology mean the same as the Latin equivalents: "operations" and "cooperation". Therefore to do is to be, and to be is to do; but essence is being as well. We can become one with God's being through our energies being in total unison with his energies, even though his being remains essentially inaccessible. This process of becoming God in practice--but not in essence--is called "Theosis", or its Latin equivalent, "Deification".
Cont