One of the main differences between Orthodox and Reformed soteriology is a different idea of punishment. It would seem as though both Orthodox and Reformed churches suffer from unintended consequences "in the pews" (or "in the nave" in our case). While Orthodox homilies can, indeed, come away sounding like our Faith is allergic to anything even resembling divine wrath, Reformed churches often come across as making the Father's offended justice that of a violent, vindictive, bloodthirsty Tyrant.
We have to be careful with how words are translating in some biblical passages. 2 Thess. 1.8-9, for example, is often translated as "In a flame of fire, giving vengeance to them who know not God, and who obey not the gospel of our Lord Jesus Christ. Who shall suffer eternal punishment in destruction, from the face of the Lord..." In the Greek, (you can compare HERE), we see that the words commonly translated as "vengeance"--εκδικησιν--and "punishment"--δικην--are all related, not to penal retribution or satisfaction, but simple "righteousness" or "straightening" (δικαιοσύνη). Granted, this righteousness will be imposed on the unrighteous apart from their will, and it will be permanent (αἰώνιον), but when we say “destruction,” what will that be? What is ὄλεθρον, really? Is it done with a violent, offended connotation, the way we usually refer to “punishment”? Or is it “ruin,” as in the sense of something undergoing “de-(con)struction”? Young’s Literal Translation of v. 9 would seem to agree with the latter:
who shall suffer justice -- destruction age-during -- from the face of the Lord, and from the glory of his strengthHere we have men suffering, indeed, and eternally so, but why? Because the justice—the setting straight of what was crooked, in which what is crooked is forcibly deconstructed, or destructed—is imposed on the wicked, but not because of a god who decides he’s going to “make this hurt.” It hurts because we don’t want it, not because God wants to make us suffer.
And I would disagree strongly with your idea that sin isn’t “really… a big deal in EO thought.” I would invite you to read the two posts again, wherein I’d say it’s fairly clear that God lets not one crooked way go unstraightened, regardless of how a person wedded to his iniquity might feel about it on judgment day. Therefore, sin should hardly be seen as "barely worthy of irritation,"
As it so happens, we are studying St. Athanasius' On the Incarnation of the Word in Patristics--a reread for me, but a much needed one--and the beginning section seems to address quite well what we're discussing here, namely, the reaction of God to sin.
In Chapter 3, we see the consequences for sin. CCEL has a nice section headers above these chapters here; we see that God has made "Creation out of nothing," with "Man created above the rest, but incapable of independent perseverance. Hence the exceptional and supra-natural gift of being in God’s Image, with the promise of bliss conditionally upon his perseverance in grace."
(So, then, all of Creation's existence is grounded on nothing less than the pure will of God; if we separate ourselves from His life by our shortcoming, we begin the process of degenration--or "de(con)struction, or destruction--with the end result being less and less existence, to the point of eventual ruin, which is the concept I'm referring to as ὄλεθρον from 2 Thess 1.9).
Chapter 6: "The human race then was wasting, God’s image was being effaced, and His work ruined. Either, then, God must forego His spoken word by which man had incurred ruin; or that which had shared in the being of the Word must sink back again into destruction, in which case God’s design would be defeated. What then? was God’s goodness to suffer this? But if so, why had man been made? It could have been weakness, not goodness on God’s part."
(We thus see the first indication of something approaching God's honor being besmirched, though there is no indication here of God being "concerned" with His own reputation but rather with being faithful to His own purpose.)
Chapter 7: "On the other hand there was the consistency of God’s nature, not to be sacrificed for our profit. Were men, then, to be called upon to repent? But repentance cannot avert the execution of a law; still less can it remedy a fallen nature. We have incurred corruption and need to be restored to the Grace of God’s Image. None could renew but He Who had created. He alone could (1) recreate all, (2) suffer for all, (3) represent all to the Father."
(Indeed, God will not refrain forever from straightening the wicked (crooked) paths. The righting of all wrongs is more important, ultimately, than "happiness." The problem with Reformed views of things like this, however, is that the wrongs to be righted are not primarily ones of law, but of ontology and corruption, ending in death. We are presented to the Father as whole because for this were we created. A deathbound penitent will still die; we must not only be delivered from transgression of a law but of the mortal consequences thereof.)
Chapters 8-9: "The Word, then, visited that earth in which He was yet always present ; and saw all these evils. He takes a body of our Nature, and that of a spotless Virgin, in whose womb He makes it His own, wherein to reveal Himself, conquer death, and restore life."
"The Word, since death alone could stay the plague, took a mortal body which, united with Him, should avail for all, and by partaking of His immortality stay the corruption of the Race. By being above all, He made His Flesh an offering for our souls; by being one with us all, he clothed us with immortality."
(Again, one can hardly call sin "not serious" when the Word calls such deeds evil and lead to dissolution and corruption in the grave.)
Ch 13: "Here again, was God to keep silence? to allow to false gods the worship He made us to render to Himself? A king whose subjects had revolted would, after sending letters and messages, go to them in person. How much more shall God restore in us the grace of His image. This men, themselves but copies, could not do. Hence the Word Himself must come (1) to recreate, (2) to destroy death in the Body."
(This is telling. What is God's concern? His reputation before mere created beings? On the contrary; He is concerned not with punishing us, but with restoring us. His wrath is not punitive, but corrective; He de-structs so that He can con-struct. Whether we like this or not when He imposes this upon us is another matter.)
Ch 25: "Why the Cross, of all deaths? (1) He had to bear the curse for us. (2) On it He held out His hands to unite all, Jews and Gentiles, in Himself. (3) He defeated the “Prince of the powers of the air” in His own region, clearing the way to heaven and opening for us the everlasting doors."
(This was a search and rescue, not a placating of a God who was determined to make punishment hurt because He was offended.)
In short, one can hardly say, if one pays attention to the hymns regarding God's wrath and to the explications of St. Athanasius, that God will allow for even one iota of shortfalling, of missing the mark of perfection to go without being fulfilled and brought to its plenitude of righteousness at the end of all things--and so our life is given to us through Christ in order that we might be made ready for that End and not hate the light of that day, preferring instead our own dark and crooked ways.