Literally, theosis means "divinization" or even "deification." In Catholic orthodoxy the term means "to make holy." This is accomplished by detachment from sin and the unnecessary things of the world, and the seeking of God through prayer and the Sacraments. One can say that the process begins with Baptism or the decision to receive that Sacrament (the individual's belief in response to God's prevenient grace), and continues as long as the person remains in the state of grace, up until the time judgment and resurrection. Some modern authors have carried the concept of theosis to the impossible conclusion that man is evolving into God. (E.g. Pierre Teilhard de Chardin and his vertical evolution toward the "Omega point.")

For it is thus that you will both controvert them in a legitimate manner, and will be prepared to receive the proofs brought forward against them, casting away their doctrines as filth by means of the celestial faith; but following the only true and steadfast Teacher, the Word of God, our Lord Jesus Christ, who did, through His transcendent love, become what we are, that He might bring us to be even what He is Himself.

St. Maximus the Confessor wrote, "A sure warrant for looking forward with hope to deification of human nature is provided by the incarnation of God, which makes man god to the same degree as God Himself became man." and "let us become the image of the one whole God, bearing nothing earthly in ourselves, so that we may consort with God and become gods, receiving from God our existence as gods." For it is clear that He who became man without sin (cf. Heb. 4:15) will divinize human nature without changing it into the divine nature, and will raise it up for His own sake to the same degree as He lowered Himself for man's sake. This is what St. Paul teaches mystically when he says, '...that in the ages to come He might display the overflowing richness of His grace' (Eph. 2:7)."(page 178 Philokalia Volume II)

I answer that, This question depends on the preceding. For if grace is the same as virtue, it must necessarily be in the powers of the soul as in a subject; since the soul's powers are the proper subject of virtue, as stated above (56, 1). But if grace differs from virtue, it cannot be said that a power of the soul is the subject of grace, since every perfection of the soul's powers has the nature of virtue, as stated above (55, 1; 56, 1). Hence it remains that grace, as it is prior to virtue, has a subject prior to the powers of the soul, so that it is in the essence of the soul. For as man in his intellective powers participates in the Divine knowledge through the virtue of faith, and in his power of will participates in the Divine love through the virtue of charity, so also in the nature of the soul does he participate in the Divine Nature, after the manner of a likeness, through a certain regeneration or re-creation.

O God, + who hast established the nature of man in wondrous dignity, and even more wondrously hast renewed it, grant that through the mystery of this water and wine, we may be made partakers of His divinity, who has deigned to become partaker of our humanity, Jesus Christ, Thy Son, our Lord, who liveth and reigneth with Thee, in the union of the Holy Ghost, world without end. Amen.

N.B. This is crackpot stuff
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Omega point is a term invented by French Jesuit Pierre Teilhard de Chardin to describe the ultimate maximum level of complexity-consciousness, considered by him the aim towards which consciousness evolves. Rather than divinity being found "in the heavens" he held that evolution was a process converging toward a "final unity", identical with the Eschaton and with God. According to Teilhard and the Russian scholar and biologist Vladimir Vernadsky (author of The Geosphere 1924 and The Biosphere 1926), the planet is in a transformative process, metamorphosing from the biosphere into the noosphere.