The Word became flesh to make us 'partakers of the divine nature'
2 Peter 1:4
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.
St. Irenaeus, Adv. haeres (Against Heresies)
For the Son of God became man so that we might become God.
St. Athanasius, De inc. (On the Incarnation)
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 Eastern Catholic tradition emphasizes a number of beliefs or attitudes regarding the spiritual life. These include:
The central emphasis of Eastern Catholic spirituality is on the important belief that we are called "to become partakers of the divine nature" (2 Peter 1:4), not merely to be 'saved' from sin. We truly do become filled with the Holy and Gracious Life of the Triune God at Baptism, and do become true children of God.
This participation in the divine nature is commonly called "divinization" or "deification." We are invited to live the very life of God, to be intimately related to God, to be united to Christ, and to have the Holy Spirit dwell within us! The Church Fathers saw this as the reason for Christ's coming: "God became man so that man might become God." (St. Athanasius).
Our justification comes from the grace of God. Grace is favor, the free and undeserved help that God gives us to respond to his call to become children of God, adoptive sons, partakers of the divine nature and of eternal life.
Cf. Jn 1:12-18; Jn 17:3; Rom 8:14-17; 2 Pet 1:3-4
Catechism of the Catholic Church, 1996