The following argument is vital to the debate between the standard gospel vs. your Greek Orthodox theology.
A works-based Orthodox theology will argue that some have greater sin than others. That is not the gospel.
(James 2:8-12) "If you really fulfill the royal law [which says] ... “You shall love your neighbor as yourself,” you are doing well. But if you show partiality, you are committing sin and are convicted by the law as transgressors. For whoever keeps the whole law but fails in one point has become guilty of all of it. For he who said [the 7th Commandment], “Do not commit adultery,” also said, [the 6th Commandment] “Do not murder.” If you do not [break the 7th] ... but do [break the 6th], you have become a transgressor of the law. So speak and so act as those who are to be judged under the law of liberty."
What it's saying is: if you don't sin in some areas - but you do sin in other different areas -- overall you're still a law-breaker in God's eyes. Because all it takes is one transgression to be a law-breaker.
MST, if you think that
some people have more dirt than others, listen to what Paul said:
"Therefore you have no excuse, ... every one of you who judges. For in passing judgment on another you condemn yourself, because you, the judge, practice the very same [evil] things."
Therefore, the importance of grace and mercy from God is that you cannot be saved and sanctified by keeping commandments. Yes, we must keep the commandments to please God ... but doing good works don't save or sanctify you.
Both being saved, and subsequent sanctification, are by faith.
(Galatians 3:2-3) - "Let me ask you only this: Did you receive the Spirit by works of the law or by hearing with faith? Are you so foolish? Having begun by the Spirit, are you now being perfected by the flesh?"
This is where
Orthodox diverges from the basic gospel. And if the early church in Antioch, during the lifetime of the apostles, could go into false teaching, don't assume that the later church a few hundreds years after that, were immune from false teaching.