Greek Orthodox name doesn't particularly pertain to Greece, it is the church of the Eastern Roman Empire (Byzantine), and was conducted in the Greek language. As you say, it should irk all Christians, and everyone who respects history. As Christians were offended when the Taliban blew up Buddhist statues, everyone should unite against this muslim extremism.
What exactly were the terms of the treaty? Can the UN designate any building in the world as a “World Heritage Site” and then the country which it is in can do nothing about it?
Conceivably the USA could never get rid of the UN if it were designated as a “World Heritage Site.”
Don’t get me wrong - I do not see this as a good thing culturally...it’s just that legally Erdogan may have the power to do this.