I've heard protestants make the allegation that the Catholic Church teaches the lie of Serpent in Genesis that "ye shall be as gods." The sources they provide are thus:

The Catechism of the Catholic Church says that "... the Son of God became man so that we might become God. The only-begotten Son of God, wanting to make us sharers in his divinity ... assumed our nature so that he ... might make men gods." -- Catechism of the Catholic Church, quoting St. Athanasius and St. Thomas Aquinas: (The Wanderer Press, 1994), par. 460, p. 116 taken from Occult Invasion by Dave Hunt, pg. 336

I searched google and discovered Wikipedia's article entitled Divinization (Christian):

According to Jonathan Jacobs, there were many and varied appeals to divinization in the writings of the Church Fathers. As what he asserts is "just a small sample", he lists the following:

St. Irenaeus of Lyons stated that God "became what we are in order to make us what he is himself."
St. Clement of Alexandria says that "he who obeys the Lord and follows the prophecy given through him . . . becomes a god while still moving about in the flesh."
St. Athanasius wrote that "God became man so that men might become gods."
St. Cyril of Alexandria says that we "are called 'temples of God' and indeed 'gods', and so we are."
St. Basil the Great stated that "becoming a god" is the highest goal of all.
St. Gregory of nαzιanzus implores us to "become gods for (God's) sake, since (God) became man for our sake."

Referring to such declarations by the Fathers, the Oxford Dictionary of the Christian Church says that the central tenet of deification is that, through the incarnation of his Son, God has called human beings to share God's own life in the Son. It quotes Athanasius: "The Word became flesh … that we, partaking of his Spirit, might be deified" (De Decretis, 14); and Cyril of Alexandria: "We have all become partakers of Him, and have Him in ourselves through the Spirit. For this reason we have become partakers of the divine nature" (In Ioannem, 9).

Saint Augustine pictured God telling him: "I am the food of grown men, grow, and thou shalt feed upon Me, nor shalt thou convert Me, like the food of thy flesh, into thee, but thou shalt be converted into Me." "To make human beings gods," Augustine said, "He was made man who was God" (sermon 192.1.1) This deification, he wrote, is granted by grace, not by making part of the divine essence: "It is clear that he called men gods being deified by his grace and not born of his substance. For he justified, who is just of himself and not from another, and he deifies, who is god of himself and not by participation in another. … If we have been made sons of god, we have been made gods; but this is by grace of adoption and not of the nature of our begetter" (en. Ps. 49.1.2).

The Fathers spoke of the process of deification as begun, at least in foreshadowing, in baptism, and so as already effected in the baptized. Clement of Alexandria wrote: "Being baptized, we are illuminated; illuminated we become sons; being made sons, we are made perfect; being made perfect, we are made immortal. 'I', said He, 'have said that ye are gods, and all sons of the Highest." Hippolytus: "He (man) is made God by water and the Holy Spirit after the regeneration of the laver.""Thy body shall be immortal and incorruptible as well as thy soul. For thou hast become God."

However, full deification was seen as occurring only after death. Augustine said, "Our full adoption as sons will take place in the redemption of our body. We now have the first fruits of the spirit (Rom 8:29), by which we are indeed made sons of God. In other respects, however, since we are not yet finally saved, we are therefore not yet fully made new, not yet sons of God but children of the world."

...

The importance of divinization (theosis) in Roman Catholic teaching is evident from what the Catechism of the Catholic Church says of it:

"The Word became flesh to make us "partakers of the divine nature": "For this is why the Word became man, and the Son of God became the Son of man: so that man, by entering into communion with the Word and thus receiving divine sonship, might become a son of God." "For the Son of God became man so that we might become God." "The only-begotten Son of God, wanting to make us sharers in his divinity, assumed our nature, so that he, made man, might make men gods." (The Catechism of the Catholic Church, 460)

Divinization has been taught by Catholic theologians, including the most authoritative: Saint Thomas Aquinas wrote: "The gift of grace surpasses every capability of created nature, since it is nothing short of a partaking of the Divine Nature, which exceeds every other nature. And thus it is impossible that any creature should cause grace. For it is as necessary that God alone should deify, bestowing a partaking of the Divine Nature by a participated likeness, as it is impossible that anything save fire should enkindle." He also wrote of God's "special love, whereby He draws the rational creature above the condition of its nature to a participation of the Divine good." And he quotes with approval the statement by Saint Augustine, "God was made man, that man might be made God", saying that it was necessary for the restoration of the human race that the Word of God should become incarnate, since it is through Christ's humanity that full participation of the Divinity is bestowed on us.

The Roman Rite liturgy expresses the doctrine of divinization or theosis in the prayer said by the deacon or priest when preparing the Eucharistic chalice: "By the mystery of this water and wine may we come to share in the divinity of Christ who humbled himself to share in our humanity."

I find this a bit confusing as Divinization not a subject of I've heard of before. The protestants are implying that the Catholic/Orthodox doctrine of Divinization/Theosis, as well as the teachings of the New Agers and Mormons, have their origins in the lie of the serpent in Genesis that "ye shall be as gods."

How exactly is Divinization / Theosis different from the lie of the serpent in Genesis that "man shall be as gods," New Age teachings that "we're all gods," and Mormonism?

How can these objections to Catholicism be countered?

Thanks in advance.

Could anyone shed some light on this?

Thanks.

The easy answer is that we don't believe that we literally become deities, but only use the phrase "become gods" in a rhetorical sense, referring to the paradox of the Incarnation and the Redemption, how God became man so that we men might become more like Him.  Therefore, the Protestant assertion is typical -- they assert that we believe something that we do not, casting aspersions and acting suspiciously towards it, in order to justify their unwarranted belief that they have a "purer" and "simpler" religion that is more aligned with their melodramatic anthropomorphisation of God's love and the generosity of Our Lord in the Gospels.  Or else they deliberately misinterpret our beliefs or interpret them in an unjustly cynical manner, in order not to refute them, but to give the impression to themselves that they have refuted them.

Divinisation/theosis/sanctification refer to the participation of the man in the state of grace in the life of God, since being justified and having sanctifying grace means that the Holy Trinity is literally dwelling within the soul.  Since all good comes from God, any time one commits a good action, one is actually only passively participating in an action of God's grace, and thus Our Lord is actually committing the good action through the soul who responds to Him, who only coöperates in His work.  As the soul is involved in more and more of the Divine Life this way, she becomes purified and more attuned to the prompts and desires and vision and presence of the Blessed Trinity Itself.  These good actions are not forgotten in Heaven, and are kept in the mind of God as the soul's merit.  Therefore, the soul becomes closer to God as she is elevated to Him, and, after death, will (in a certain sense) see all things -- including the self --as God sees them -- this is the Beatific Vision.

Anyway, I doubt most Protestants are open to hearing such things.  They will see foul play where they will, since they do not truly believe in the Incarnation, at least not in any meaningful or practical or serious way.  They do not believe in spiritual and moral progress.  They do not believe in increases and losses of sanctifying grace, or the absolution of sins, or the expiation of sins, or whatever.  They think that it is impossible to please God except through having a simplistic and ahistorical "faith" in Him, one which is completely and continually made up by themselves and their vain imaginings.  And even within this "faith," God does not actually forgive their sins, but "covers"/ignores them completely, such that none of their sins count.  Their false assurance of salvation, therefore, is entirely self-referential and emotional.  Theirs is an emotivist religion; thus, since they feel negative things about the True Faith, almost all of their engagements with one defending it will be governed by the dominating ill-feelings they harbour towards their own idea of it.  That is to say, it is almost impossible to reason with Protestants, since their whole lives and mindsets and references are already outside the bounds of reason.

The Byzantine Church often talks about Theosis in exactly the manner described above.

Rev. Father Garrigou-Lagrange in his work Three Ways of the Spiritual Life [Les trois conversions et les trois voies],  (Westminster, MD: Newman Press, 1950), shows how the Protestant heretics have degraded the notion of grace and what is the true nature of supernatural grace.

In this sense we are "divinized" by God's grace just as metal is transformed by fire.

And on top of that, God is an alchemist for he purifies and anoints, turning dirty souls into gold.