How do the Orthodox interpret the numerous verses that make reference to God's predestination of the elect? Because you can't just handwave those verses away or give them some transparently inaccurate interpretation. They're very clear in their language and meaning, and the theme is touched upon repeatedly in both the Gospels and the Epistles. Of course we can argue and speculate as to the nature of predestination/determinism vs. free will and how both concepts seem to exist simultaneously in scripture (I believe this is one of the topics that Paul refers to about us seeing through a glass darkly - such things are essentially impossible for us to understand from our human perspective and can only be reconciled in the omniscient mind of God which exists outside of space and time entirely).
One point I'd like to add to this, which I think tends to get overlooked, is that when Scripture talks about predestination, like in Romans 11, it's not talking about God deciding the fate of the individual, but of collective groups - in this case, that of the nation of Israel. This is an important nuance that completely transforms how we think about this topic.
It might also explain why the debate about the particular concepts surrounding the Calvinistic conception of predestination never arose until the 16th century, in a historically novel time and place of post-Renaissance, early modern Western Europe, with an individualistic orientation that really never existed anywhere before that, and an entirely new way of encountering Scripture, the literate man reading his own printed copy of the Bible by himself in his study and thinking about what he was reading in very individualistic terms. Contrast to the communal, liturgical context in which virtually all people encountered Scripture before that.
With that understanding in mind, a lot of the contentious framing of this subject falls apart.