Theosis is possible through the uncreated energies of God
In the Orthodox Church of Christ, man can achieve theosis because the Grace of God, according to the teaching of the Holy Bible and of the Church Fathers, is uncreated. God is not only essence, as the Westerners believe, but also energy. If God was only essence, we would not be able to join, to commune with Him, because the essence of God is terrifying and inaccessible to man, according to "You can not see My face; for there shall no man see Me, and live" (Ex. 33:20).
Let us mention some specific example regarding humans. If we touch a live bare cable, we would die. However, if we connect a light bulb to the cable we are illuminated. The energy of the electric current we see, enjoy, and it helps us. Its essence we cannot hold. Something similar, if we may say, happens with the uncreated energy of God.
If we could be connected with the essence of God, we could also become in essence gods. Namely, everything would have become gods, there would have been a confusion and nothing would have essentially been god. Namely, what they believe in the eastern religions, such as Hinduism, where god does not personally exists, but is a vague power, scattered over all the world, on the people as well as on the animals and on the materials (Pantheism).
If again God had only incommunicable divine essence without His energies He would have remained a self sufficient God, closed into Himself and non-communing with His creations......
With these, His uncreated energies, God created the world and continues to sustain it. He gives essence and existence to our world with His essence creating energies. He is present in nature and sustains the universe with His sustaining energies. He enlightens man with His enlightening energies. He sanctifies him with His sanctifying energies. And finally He makes him god with His Godly energies. So with His uncreated energies, Holy God enters nature, in the world, in history, in the lives of people.
The energies of God are divine energies. They are also God without being His essence. They are God that is why they make man god. If the energies of God were not divine, uncreated energies, then they would not be God, they would not be able to make us god, to join with God. There would have been an unbridgeable distance between God and people. However, by God having divine energies and with these energies joining with us, we can communicate with Him and join with His Grace, without equating with God, as it would have happened if we were joining with His essence.
We therefore join with God through His uncreated energies, and not through His essence. This is the mystery of the Orthodox Faith and of our life.
This, the Western heretics cannot accept. Because they are rationalists, they cannot differentiate between essence and energies of God and thus maintain that God is only essence. For this they cannot speak about theosis of man. For how could man be made god since they do not accept uncreated but created the divine energies? So, how can something created namely, outside of God Himself make god the created man?
During the 14th century there occurred a great disturbance in the Church, which was instigated by a western monk, Varlaam. He heard that the Agiorite monks were speaking about theosis. He was informed that they became worthy, after a great struggle, cleansing themselves from the passions and with a lot of prayer, to join with God, to receive experience of God, to see God. He heard that they could see the uncreated light, which was seen by the Apostles at the Transfiguration of the Saviour at mount Tabor.
However, Varlaam having the western, heretic, rationalist spirit could not perceive the genuine divine experiences of these humble monks, so he started to accuse the Agiorite that they were possibly deceived, were heretics and idolaters. He would say, for example that it was impossible for anyone to see the Grace of God, because he (Varlaam) did not know anything about the difference of essence and uncreated energies of God.
Then, the Grace of God brought forth a great and enlightened teacher of our Church, the Agiorite Saint Gregory Palamas, Archbishop of Thessaloniki. With great wisdom and enlightenment from God, but also from personal experience, he said and wrote a lot and taught according to the Holy Scriptures and the Holy Tradition of the Church, that it is uncreated the light of the Grace of God, it is divine energy. That they actually see this light those who became godly (through theosis) men as the highest, and paramount experience of theosis and seeing in this light of God. This is the glory of God, the brilliance, the Taborian light, the light of Resurrection of Christ and of the Pentecost and the illumined cloud of the Old Testament. Actual uncreated light of God and not symbolic as Varlaam and his likes falsely believed.
In continuation all the Church with three great Synods in Constantinople, justified Saint Gregory Palamas and declared that the life in Christ is not simply the moralizing of man but his theosis, which means participation in the glory of God, vision of God, of His Grace and of His uncreated light.
Until today the Westerners consider the divine Grace to be created, the energy of God. This is unfortunately one of our many differences, which must be taken seriously into consideration in the theological dialogue with the Roman Catholics. It is not only the "Filioque", the primacy of jurisdiction and the "infallibility" of the Pope, the basic differences between the Orthodox Church and the Papists. It is also the above. If the Roman Catholics do not accept that the Grace of God is uncreated, we cannot join with them, even if they accept everything else. For who will operate the theosis, if the divine Grace is created and not uncreated energy of the Most Holy Spirit?
By Archmandrite George, Abbott of the Holy Monastery of Saint Gregory, "Theosis as the goal of man's life", page 34-41
From the magazine "In Conscience". Issue of the Holy Monastery of Great Meteora, Dec 2006.