Of course, the Holy Fathers maintain that we can attain deification in the Church. However, deification is an endowment from God, not something we attain on our own. Naturally, we must desire, we must struggle and prepare to be worthy and willing to receive and preserve, this great endowment from God, since God wishes to do nothing without our consent. Nevertheless, deification is a gift from God. That is why the Holy Fathers say that we, on the one hand "experience" deification, while God, on the other hand, "works" deification.
We can distinguish some necessary prerequisites in man’s journey to deification.
According to the Holy Fathers, the first requirement for deification is humility. Man cannot be set on the path to deification, accept divine Grace, come into fellowship with God, without blessed humility. He needs humility even just to realize that the purpose of his life is deification. Without humility, how will you acknowledge that your life’s purpose lies out of yourself, that it lies in God?
As long as man lives egotistically, anthropocentrically, autonomously, he places himself as the centre and purpose of his life. He believes he can self-perfect, self – define and self-deify himself. After all, this is the spirit of contemporary civilization, philosophy and politics: to create a better, more just world but autonomously, a world that places man at the centre without reference to God, without acknowledgement that God is the source of all good. This is the error committed by Adam who believed that he could become god and be fulfilled through his own powers. All humanistic creeds of all ages commit Adam’s error. They do not consider communion with God a necessity for man’s perfection.
Everything Orthodox is Theanthropically-centred, it has Godman Christ at the centre. Everything that is not Orthodox -Protestantism, Papism, Masonicism, Jehovah’s witnesses, atheism- everything outside Orthodoxy has the same denominator: the centre is man. For us, Christ is the centre. Thus, it is easy to become a heretic, a Jehovah’s witness, a Mason or anything else, but it is difficult to become an Orthodox Christian. To become an Orthodox Christian, you must accept Christ, and not yourself, as the centre of the world.
Therefore, the beginning of the path towards deification is humility, namely to realize that our life’s purpose lies not within us but within our Father, Maker and Creator.
Furthermore, we must be humble, to realize that we are ill, filled with weaknesses and passions.
The one who begins the journey to deification must have ceaseless humility in order to keep himself continually on this journey. For, if he accepts the thought that he is doing well and advancing on his own, then pride overtakes him. He loses what he had gained and needs to start anew, to be humble, to see his weakness, his human illness and not to rely on himself. He must rely on God’s Grace in order to be kept continually on the journey to deification.
That is why, in the lives of our saints, we are impressed by their great humbleness. Although they were very close to God, shone in the light of God, worked miracles, gave forth myrrh, yet at the same time they held themselves in low esteem, believed they were far from God, that they were the worst of men. This very humility made them gods by Grace. b) The exercise of asceticism
The Fathers remark that deification has stages, beginning with the lower ones and proceeding to the higher ones. Having earned humility, we begin, with repentance and with much patience in our daily struggle in Christ, the practice of the application of Christ’s holy commandments in order to be cleansed from our passions. Moreover, the Holy Fathers say that God, Himself, lies hidden in His commandments and when the Christian keeps them from love of and faith in Christ, then he is in fellowship with Him.
In accordance with the Holy Fathers, this is the first stage of deification which is called "praxis". It is the practical guidance, the beginning of the journey to deification.
Naturally, this is not at all easy because the struggle to uproot the passions from within us is great. Much effort is required so that little by little our uncultivated inner self is purified from the "thorns and rocks" of passion and is cultivated spiritually, so the seed of God’s word may fall and bear fruit. Great and ceaseless violence towards ourselves is needed for all this. Wherefore the Lord said: "the Kingdom of God suffereth violence and the violent take it by force" (Matthew 11:12). Then again the Holy Fathers teach: "Give blood and receive Spirit". In other words, you cannot receive the Holy Spirit unless you offer your heart’s blood in the struggle to be purged from passions, in the struggle to repent truly and deeply and to acquire the virtues.
All the virtues are aspects of the one and great virtue, the virtue of love. When the Christian acquires love, he has all the virtues. Love is what banishes from man’s soul the cause of all evil and the cause of all passions, which according to the Holy Fathers is selfishness. All evil within us, emanates from vanity which is the diseased love for one’s own self. Hence, our Church has ascetic endeavours. Without ascetic endeavours, there is no spiritual life, no struggle, no advancement. We obey, fast, keep vigils, labour with prostrations and stand on our feet for hours in order to be cleansed from our passions. If the Orthodox Church ceases to be ascetic, it ceases to be Orthodox. It no longer helps man to be rid of his passions and become a god by Grace.
The Fathers of the Church develop a great and thorough anthropological teaching about the soul and man’s passions. According to the Fathers, there are in the soul the intelligent and the passible aspects or powers. The passible aspect contains the incentive and desiring powers of the soul. The intelligent aspect contains the rational actions of the soul, i.e. reckonings and thoughts. The incentive aspect is the positive or negative sentiments – love, hate. The soul’s desiring power is the desire for sensuality and for pleasure, avarice, gluttony, carnal desires, the human passions. If these parts of the soul, the intelligent, the intentive and the desiring powers, are not purified, man cannot receive within himself God’s Grace. He cannot be deified. The intelligent aspect is cleansed through watchfuleness, which is the continuous guarding of the mind’s thoughts: That is to say, by retaining the good thoughts and driving away the evil ones. The incentive aspect is cleansed through love. And lastly, the desiring power is cleansed through sobriety. All of them in common are purified and sanctified through prayer.
c) The Holy Sacraments and prayer
Christ settles Himself in man’s heart through the Holy Sacraments – Holy Baptism, Chrismation, Holy Confession, the Divine Eucharist. Those Christians who are in fellowship with Christ, have God and His Grace in them and in their hearts because they are baptized, have confessed, received Holy Communion.
However, passions overshadow Divine Grace, just like the ash covers the spark. With exercise in virtues and with prayer the heart is purified from them, the spark of Divine Grace is rekindled and the faithful feels Christ in his heart, which is the centre of his being.
Every prayer of the Church helps purify the heart. Especially helpful, though, is the so-called monologistic prayer or "Prayer of the heart" or "Jesus prayer", the prayer: "Lord Jesus Christ, Son of God, have mercy on me the sinner". This prayer, which from all times is handed down on Mount Athos, has the following advantage: being monologistic, i.e. only one sentence, it helps to concentrate our attention easily on our mind. Through concentration we plunge our mind into the heart and are cautious that the mind is not distracted by other things or meanings, either good or evil, but engaged with God only.
Practice of the Prayer of the Heart, which in time, with God’s Grace, can become incessant, is a science in itself, a holy art which the Saints of our Faith describe in detail in their holy writings and in an extended anthology of patristic texts called "The Philokalia".
This prayer helps people and gives them joy. When Christians progress in this prayer, at the same time living in accordance with the holy commandments of Christ and the Church, then they are made worthy to receive an experience of the Divine Grace. They start to taste the sweetness of God’s communion and by experience- "taste and see that the Lord is gracious" (Psalm. 33:9). For us Orthodox, God is not an idea, something we simply think about or talk about or read about. He is a person, with whom we come into a living and personal communion, something which we live and of whom we receive an experience.
We then understand what a great, unspeakable and inexpressible joy it is to have Christ in us and to be Orthodox Christians.
It is of great help for Christians who are out in the world, amidst the various daily concerns and activities, to find at least a few minutes of peace to practise this prayer.
Of course, all the labours and duties done according to God’s will, when performed with humbleness and love, sanctify the Christian. But prayer is a necessity. In a peaceful room (preferably after spiritual preparation of lighting the small oil lamp in front of the icons, and with burning incense) as far away as possible from noise and distractions and after a period of rest from thoughts, the Christians can plunge their mind into the heart by reciting the prayer, "Lord Jesus Christ, Son of God, have mercy on me a sinner". What peace and strength the souls derive from this tranquillity of God! What great support this prayer brings to their souls throughout the whole day, so they remain at peace without irritability or anxiety. It allows their soul’s faculties to be in harmony and unity.
Some people seek a bit of spiritual tranquillity through artificial means in other deceived and demonic places, such as the so-called Oriental religions. They try to find some peace with external exercise, meditation etc., to achieve a balance between the soul and the body. The error is that man in such a situation, trying to wipe out the various thoughts and the material world, does not in fact converse with God, but monologises (speaks with himself). He ends up with anthropocentrism and fails.
(From the book “The Deification as the purpose of man’s life”, Archimandrite George, Abbot of the Holy Monastery of St. Gregorios of Mt. Athos, 1997)