Sin As A Disease And It's Cure
In the Eastern Orthodox understanding of salvation, sin is understood as a disease. Not just in the sense of a metaphor but quite literally -- sin is understood as the disease leading to death. It is from this death and captivity that the Son of God has delivered us by His becoming incarnate of the Holy Theotokos (Mary). By taking upon Himself our human nature and by living a sinless life, He raised our nature to the likeness of God which was its true purpose in creation. This is how Orthodoxy understands the concept of the crucifixion as the sacrifice of the Lord -- that He offered Himself unto the Father - the very fullness of His humanity being offered as a living sacrifice (Romans 12:1). The fullness of His humanity thus offered -- to the fullest extent a human life can be offered: namely even to the point of accepting death.

Obedient to the Divine Will, even unto death, He has nailed sin to the cross. By willingly accepting death for our sake He moreover descended into Hades where, held captive by death, all generations of humanity from Adam until then were waiting for the Promised Redeemer - the Seed of the Women who was to crush the head of the serpent. And it was there, that the grave met it's defeat, and death itself died, conquered by the Cross - the Humility of Him Who is the King of Glory. And it is this very Cross that the Lord has given us, transformed from the symbol of shame and death - to the very sign of life and glory. This is the Cross giving us the strength through which we must also pick up the smaller cross of our own life, the way of repentance and humility through which we now follow the prototype set by our own Lord and God.

As far as the temptation towards sin, we must of course make every effort at fleeing from it at the slightest manifestation of it, realizing the weakness of our flesh. This is not easy -- but neither was the Cross which the Lord had to bear for our salvation. This is where the ascetic life of the Orthodox Church helps us. The fasting, prayers, and participation in the liturgical life and feasts of the church, most especially the divine mysteries of baptism, repentance, confession, and the Holy Eucharist are all verily salvific - healing our bodies, transforming our minds, and imparting to us the Grace of the Holy Spirit.

This is the fullness which the Lord has given us through the Holy Orthodox Church which is His Body, where this fullness is manifested in Holy Tradition, preserved unchanged and without corruption for 2000 years. Completing the analogy (though it's not only an analogy but also a reality), the Orthodox Church is the hospital for sinners, and Christ is the Great Physician, the divine mysteries being the medicine which heal and transform us. We are all sinners, and Orthodox Christians say in our prayer before communion 'I believe, O Lord, and I confess that Thou art truly the Christ, the Son of the Living God, Who camest into the world to save sinners, of whom I am first'. The battle against sin is a cross that all Christians must take up - for nothing less than the sake of the Kingdom of God. Yes, we are weak and we fail many times - and this is why Orthodox Christians also practice confession. Because we all have a tendency to justify our sins and take the forgiveness of the Lord for granted.

Image / Likeness Distinction in Eastern Orthodox Theology
First we note that Adam was created in the 'image' of God - and yet he was capable of falling. Orthodox theology makes a distinction between the image of God which is understood statically and all man posses from the moment of conception by virtue of being human AND the likeness of God which is understood dynamically where we can grow towards this likeness or fall away from it. It is this growing into the likeness of God that Orthodoxy understands as Theosis. This is why Salvation in Orthodoxy is not just a restoration to the pre-fall state but something incomparably greater 'what eye has not seen and ear has not heard ..' 1 Corinthians 2_9. This is why the Saints in heaven are understood to be greater in glory than Adam / Eve before the fall. Finally, the New Testament scriptures themselves speak of us being 'partakers of the Divine Nature' 2 Peter 1_4; not just emulating God's righteousness through action but literally partaking in His Uncreated Nature i.e. Divinity. Christ prays to the Father that: 'the glory which Thou Gavest Me I have given them' John 17_22 and the Apostle Paul speaks of the age to come as one where we go 'from glory to glory' 2 Corinthians 3_18.

Theosis in Eastern Orthodoxy & the Energies / Essence Distinction
'The Son of God became the Son of Man so that sons of men may become the sons of God' - St. Athanasius
The analogy commonly used in explaining theosis is that of an iron rod held over a fire. By participation of the iron in the fire, the iron will take on the very properties that the fire alone truly possesses -- so for instance a paper placed on the iron will burst into flames. But the iron does not cease to be iron. The distinction between the iron and the fire is still preserved. God is always God; and we remain for ever creatures. Equally importantly, if the iron were to move away from the fire, it will lose those properties in a short time. Eastern Orthodoxy makes a distinction between the essence (ousia) of God which is utterly transcendent / unknowable and the energies (energia) of God which permeate creation and especially man -- who is created in the very image of God. Orthodoxy also makes a firm distinction between God (who is uncreated) existing in three hypostases (persons) Father, Son, Holy Spirit - and created beings (humans / angels). Deification is participation in the 'divine nature' (2 peter 1_4) via the energia / grace of God which is God himself. NOTHING can ever participate in the essence of God. Thus there is a firm and unbridgeable chasm between the Trinity and everything else. The understanding of 'theosis' is to become by grace what God alone is by nature. But this becoming is never independent of God but rather only in the context of continued communion with the Triune God.