So what is Orthodox (with a capital 'O') teaching in regards to sin?
The view of sin in Orthodoxy is somewhat manifold. There are mountains of Scripture supporting our view, but I'll stick with a few pertinent Scriptures that I can think of off the top of my head.
In the first line, we follow the Gospels, and look at a title of Christ that usually goes overlooked:
Mark 2:17 And when Jesus heard it, he said to them, “Those who are well have no need of a
physician, but those who are sick. I came not to call the righteous, but sinners.”
Christ is the Physician of our souls, come to
heal sinners. This means that sin is ultimately a disease to be healed by a Physician, not a crime to be punished by a courtroom judge. And what is the end result of sin? Death. And this ties in directly to my next point.
Sin is also something to which we are
enslaved. Looking at Romans 6:
17 But thanks be to God, that you who were once slaves of sin have become obedient from the heart to the standard of teaching to which you were committed, 18 and, having been set free from sin, have become slaves of righteousness. 19 I am speaking in human terms, because of your natural limitations. For just as you once presented your members as slaves to impurity and to lawlessness leading to more lawlessness, so now present your members as slaves to righteousness leading to sanctification. 20 For when you were slaves of sin, you were free in regard to righteousness. 21 But what fruit were you getting at that time from the things of which you are now ashamed? For the end of those things is death. 22 But now that you have been set free from sin and have become slaves of God, the fruit you get leads to sanctification and its end, eternal life. 23 For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord.
In line with sin being a disease, sin is also a fatal disease, which deprives us of life. But when we sin and fell away from God, we became slaves to sin and death. Jesus died to give us a way out of that slavery (Romans 5:12-21; 6:3-4).
If sin is a disease and something to which we are enslaved, then we are freed from it and healed of it. But where does the forgiveness part come in? We know that sin is also something that is forgiven. But is it in a purely legalistic sense? No. God is our Father, first and foremost. Sin is something that alienates us from Him. Just as the Prodigal Son became alienated from his father after wasting his inheritance in favor of loose living, so we became alienated from God after throwing away His grace and offer of eternal life, instead choosing sin and death.
Colossians 1:
17 But thanks be to God, that you who were once slaves of sin have become obedient from the heart to the standard of teaching to which you were committed, 18 and, having been set free from sin, have become slaves of righteousness. 19 I am speaking in human terms, because of your natural limitations. For just as you once presented your members as slaves to impurity and to lawlessness leading to more lawlessness, so now present your members as slaves to righteousness leading to sanctification.
20 For when you were slaves of sin, you were free in regard to righteousness. 21 But what fruit were you getting at that time from the things of which you are now ashamed? For the end of those things is death. 22 But now that you have been set free from sin and have become slaves of God, the fruit you get leads to sanctification and its end, eternal life. 23 For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord.
And again, in Romans 5:
but God shows his love for us in that while we were still sinners, Christ died for us. 9 Since, therefore, we have now been justified by his blood, much more shall we be saved by him from the wrath of God. 10 For if while we were enemies we were reconciled to God by the death of his Son, much more, now that we are reconciled, shall we be saved by his life. 11 More than that, we also rejoice in God through our Lord Jesus Christ, through whom we have now received reconciliation.
So God is angry at us, not because He wants to punish us and destroy us for being bad, but because He wanted to knock some sense into us. If you look through the Old Testament Scriptures, you will see that whenever God is angry with His people, He always says how He wants them to come back to Him, and sends His prophets to exhort them to repent. God is our Judge, yes, but He will judge us as a Father judges His children, not as a cold, impartial courtroom judge passes sentence on a convict. This is why we reject Anselm of Canterbury's idea from the 1100's that Jesus died to pay the debt to God for our sins and satisfy His offended sense of justice, and why we reject John Calvin's idea from the 1500's that God HAD to punish someone for our sins, and Jesus was the only One Who could take the full beating from God and satisfy His wrath. You should note that both Anselm and John Calvin were both lawyers. Figures that they'd invent such legalistic explanations...
Rather, Christ's death on the Cross was a means to fully share in our human experience, to defeat death, and to reconcile the entire world to Himself through the Cross. This is the ancient position of Christianity.
That would be the Orthodox position in a nutshell. I'd be happy to clarify further.