There is one God. He is the single holy entity who created and sustains the Universe. God is good, absolutely transcendent, and beyond being and non-being. He exists before and beyond all time and space—he is beyond “existence” itself. God is uncreated, unchanging, and unfathomable. All things exist in God; he is everywhere and fills all things.
God is also immanent, personal, loving, and intimately involved in the existence of all things. He is a good and merciful Father, a friend closer than a brother, and our very life.
The Holy Trinity
Since God is just a generic word, the God of Orthodox Christians is properly called the Holy Trinity. Our God has been revealed as three Persons in a union of one Being. Each Person is fully God in himself, and each is equal to the others in a never-ending movement of love. The three Persons have one Divine Essence and one will.
The three Persons have been revealed to us as the Father, the Son, and the Holy Spirit.
God the Father
The Almighty Father is wholly uncaused. He is the “font of deity”, the self-existent Person of the Trinity. He is the creator of heaven and earth, and of all things visible and invisible.
God the Son
The Son of God is eternally begotten of the Father. While the Son comes from the Father, both of them have always existed. The Son is also called the Word of God, the Logos.
Around the year 1, the eternal and transcendent Son became a finite human being, Jesus Christ. By this act, a bridge was created between humanity and God, making it possible for us to unite to him—salvation.
God the Holy Spirit
The Holy Spirit eternally proceeds from the Father. He is the giver of life and the inspiration of the Prophets. The Holy Spirit came into the Church fifty days after Jesus Christ’s resurrection (Pentecost), and he guides the Church into all truth (John 16:13). Despite the sinfulness of every one of us, the Holy Spirit will keep the Church from error until the day of Jesus Christ’s second coming.
Essence and Energies
All of us have a deep inner self that no other person knows but us. This is the realm of our inner dialogue, our thoughts, feelings, emotions, and everything that is unknowable by other people. We could call this our Essence.
We also have our outer self. This is everything that we say and do—our actions, expressions, personality traits, and all other aspects of us that people come to know us by. These are our Energies.
God has Essence and Energies as well. As with people, God’s Essence is the part of him that is unknowable. No created being can know God’s transcendent, infinite Essence; only God knows himself this way. God’s Energies are how we know God—everything he does are his Energies.
One example of divine Energies is Grace. Grace is not simply a thing, or a sort of “magic pill” he gives us. Grace is God himself—his own actions and interventions in our world. Indeed, God does not give us Grace as much as we enter his Grace—that is, his divine Energies—the light of God himself.