I want to add that I've always found that the theories of atonement the Byzantine churches have attacked are not necessarily Latin or Roman Catholic, or at least not fully endorsed by the Church of Rome. In fact, if one uses their Catechism as the official representation of Roman Catholic theology, I actually find nothing wrong with their soteriology. They make no mention of the unlimited sin that both Anselm and Aquinas taught. Rather, I see them more in Calvinistic sources that offer us a God so disconnected from as well as so irate with creation to such an extent, it is actually no different than the Islamic concept of God, not to mention the limitations of such a God, in which He is FORCED to react to iniquity in such a close-minded manner, rather than present to us a God that does not need to react to anything creation does.
A Panentheistic system does not allow for a legalistic system that goes out of hand like Calvinism. Rather, I think a legalistic system can be complimentary to a deification/sanctification system in a more allegorical sense, as has been present among the ancient Church fathers, even the Eastern ones. If this is ignored, in my opinion, this is crossing the line. I think for instance, St. Augustine needs to be given another look, and allowed to be interpreted with the best of intentions, and not through the lens of Calvin, as has been done not just by these Protestants, but unfortunately also by the likes of Fr. John Romanides (who I greatly respect and admire) and his followers.