Good topic Nektarios!
My understanding of this is as follows.
Everyone is a recipient of God's benevolence (grace). He also is drawing all men, subtly (and often not so subtly!) towards the Conqueror of death, and the trampler of satan's reign (which is drawing to a close), our Lord Jesus Christ.
31 Now is the judgment of this world: now shall the prince of this world be cast out.
32 And I, if I be lifted up from the earth, will draw all men unto me.
33 This he said, signifying what death he should die. (St.John 12:31-33)
We also know that it is God's plan (at a point no one can know with certainty) to bring this age to a close, remove the "veil" which now causes us to see the reign of God in His creation only dimly, and for all creatures to perceive the terrible (used in the old sense of the term, as in "great" and "awesome" but without the pejorative sense now commonly attached to this term) Glory of the Lord.
While it is true that all receive the uncreated energies of God in various ways (God bringing men into existance, and sustaining their existance, and otherwise showing His goodness towards all creatures), it is only by assimilation into Christ (Who according to His Humanity is consubstantial with mankind, and consubstantial with His Father according to His Divinity), that the insurmountable obstical of our mortality can be overcome, for He alone is the only man Who lived a life upon which the devil could have no claim (for He was absolutely without sin) and Who has overcome the world (overcoming death/mortality). It is only by being assimilated into the "new man" (new Adam), that our own humanity can be renewed so as to be able to receive this coming Apocalypse (lit. "revelation") as blessedness and peace.
Without such a renewal/regeneration, this revelation is going to be received as anything but blessedness. In truth, the same Glory which will be warmth and consolation to the Saints, is going to be a terrible inferno and misery for the damned. This is the real difference between the "Heavenly City" (whose inhabitants will be those who have been prepared for the revelation of the Lord of Glory), and Gehenna, where those unprepared for this final revelation will be consigned (the word "gehenna", used to describe this place, was from an infamous place in the Holy Land, which had come to be used as a garbage dump by the Jews - in short, a place to dump your undesirables.)
"Sin" (hamartia - lit. "missing the mark") then, is fundamentally a problem existing in the hearts of men, begotten/fostered by their already existing mortality, and only made clearer by the Law (this is why St.Paul speaks of the "curse of the Law" - for the Law can ultimatly only underline how often we fail, and demonstrate our absolute helplessness in accomplishing our own salvation by any of our own powers or good intentions; for indeed, the Law promises death, to all who fail to observe it with unerring exactitude - an accomplishment which the Scriptures say, only Christ accomplishes.)
The consequences/fall-out of sin, are things we can no way "blame" God for. This totally dismantles a long standing angst in many westerners, whose confessions often leave them with the impression that the "exclusion" from the lot of the blessed ("Heaven") of any individual, is ultimatly something God could be faulted for - if only God were more forgiving, more lenient, more willing to overlook our trespasses. In short, they believe He is a fundamentally cruel entity Who has set us up to fail, and is ever waiting for us to fail.
Of course, the opposite is true - He has implicitly forgiven all, and if anything, actually carefully watches for, assists, and waits on the humilitation of mankind, so that it will fully co-operate with the provision that He has made (in Christ Jesus) for their salvation. He is the unfathomably loving father of prodigals, not the offended feudal lord in the sky, grouchily waiting for us to "mess up", and should this happen, insatiably in need of satisfaction (as if He cannot forgive men their sins without such - such compulsion is the lot of pagan gods, ruled by fate and other impersonal, ultimatly murkey "eternal laws" - God on the other hand, is the only "being" which is eternal, and He is not compelled by anything - all is from His unfathomable benevolence.)
This Orthodox understanding of sin (and by unavoidable consequence, of God Himself) is the antidote to all perverse "soteriologies" proposed by men, including those which fundamentally do not perceive the obstical to our fellowship with God as being found in men and the works of the devil, but in God Himself (heterodox models of redemption, particularly any that would teach belief in "God the Problem" rather than "God the Father.")
This authentic, Apostolic understanding of sin and redemption (and ultimatly, of God) has innumerable consequences for the Church's life. Immediately, I can think of one which stands as a bone of contention between Orthodoxy and Roman Catholicism; the issue of divorce.
Both Roman Catholics and Orthodox realize divorce is a sin - even in the Old Testament (where the Law allowed for a great deal of leniency on this subject) God expresses how hateful divorce is (Malachi 2:16).
Yet in the Roman Catholic Church, there is no possibility (ignoring the sophistry surrounding annulments) of someone being divorced from a spouse, even if the innocent party in the situation, and re-marrying. Such is a sin, contrary to the evangelical purity taught by Christ.
Orthodoxy agrees with one point - it is a sin (hamartia - "misses the mark.") Yet She also realizes, in some cases, that re-marriage for many people is the lesser of two evils. For many people (and we all know who we are), the chastity of body and heart appropriate to marriage is a huge cross - and for many who find themselves on one end of a marriage which has fallen apart (after many attempts to fix the situation), living the rest of their life alone (particularly if there dependent children involved) is going to be more than they can stand.
So the Church has a choice - for the weaker brethren who opt to marry again, expell them from the Church (exommunicating them from the Holy Mysteries, thus depriving them of the means of their salvation - which to be fair, in some situations, is a last ditch way of getting people to have a change of heart), or be willing to forgive and overlook much in their weakness, with the hope they will still be able to work out their salvation.
Such liberality in some cases is itself, expressed in the Scriptures - Christ Himself allows for an exception in the case of a spouse guilty of pornea (a broad term, which pertains to sexual perversity - most likely adultery), and St.Paul expresses leniency in this regard for new-converts; if they cannot bear continuing with a pagan spouse, they may divorce them, and be allowed to re-marry a Christian at some point. However it needs to be said, even these allowances, are condescencions from the ideal - for as St.Paul indicates (though it will come with great crosses), the Christian spouse can in fact act as a means of sanctification for their heathen wife/husband, perhaps leading them one day to the gates of salvation; such would be a true demonstration of selfless love, the kind of love we are undifferentiatedly called to (but so often fail to manifest.)
The Orthodox understanding of sin, it's origin, and it's consequences, has this kind of effect on Her ministry. She is a hospital for people at varying stages of their transformation into true "sons in the Son", not a religious country club for the already perfected.