How does Coptic theology approach and explain the subject of 'theosis'? Chalcedonians use the Palamite terms 'essence' and 'energy': man participates in God's energies but not in His essence.
Theosis or Deification means "union with God" taken from the Greek Theos - God, and the word Enosis - union. Our Lord Jesus Christ asked God the Father "They also may be one in us" (Jn 17:21). He also gave us the command of Theosis "Therefore you shall be perfect, just as your Father in Heaven is perfect" (Mt 5:48), our goal in life is to accomplish perfect union with God through the grace of the Holy Spirit. Man was created in the image and likeness of God, and then sin created a gap between God and mankind, causing damage to our souls. All Christians through baptism receive the seed of Theosis, which is not only to the forgiveness of sins, reconciliation and justification, but also a restoration of God's image. The sinful inclination of our human nature should not govern our behavior anymore; instead we should strive to live a holy life looking towards Jesus Christ the author of our faith, and growing in His knowledge and sonship. The restoration and sanctification of Theosis brings us back into relationship with the Creator. St. Athanasius' presentation of Theosis was summarized as "the reintegration of the divine image of man's creation through the sanctifying work of the Holy Spirit conforming the redeemed into the likeness of the Lord Jesus Christ, and also of the believer's transition from mortality to immortality so that he is enabled to participate in the eternal bliss and glory of the kingdom of God."
Our full union with God is a union with the "energies" of God. These energies, while an extension of God, are not to be confused with the "essence" or "substance" of God, which is unknown by humans and is shared only by the Holy Trinity. Our union with God will not make us gods but will make us partners in the Divine nature in works not in essence. We will not acquire the unique characteristics of God such as being the Creator, the Omnipotent, the Omnipresent, but it will make us partners with Him in building the Kingdom by our own salvation and by winning the souls of others to the Lord Jesus Christ.