Personally, I think the explanation you gave for Orthodox (Eastern Christianity) is simplistically beautifulThanks!
I’m not 100% sure I understand the rest, but … here is my super-simplistic History of Christianity diagram I made in my phone last year for discussions like these.
So…I added Augustine for you. He is really the one who solidified the Western concept of Original Sin. That happened before the theological split between Eastern & Western theology in 1054 AD. (and LONG before settlers came to the US, if that’s what you meant.) But because of geographical distance, the Eastern church was already developing differently.
At a VERY basic level, Eastern Orthodoxy is more mystical, and Christ is saving humanity from spiritual sickness… and Western Christianity is more legal/penal, and Christ is saving humanity from everlasting punishment.
However, it isn’t accurate to say the Orthodox are more “liberal.” It is more complex than that. And from the outside, the difference isn’t evident. If you didn’t like the ritual stuff in Catholicism, Orthodoxy is 10x more so, LOL! (But I am fine with that. It is some of the Protestant stuff, tongues & being slain, that freak ME out.)
Original Sin and Substitutionary Atonement are two doctrines that I hate, and they essentially define Western Christianity. But they did not catch on in Eastern Christianity to the degree they did in the west. Most Americans have no idea of this.
In modern times, with transportation and communication, there has been a lot more “mixing,” especially since Western culture is so dominant worldwide. The average parishioner, and even some clergy, sound much like each other.
But I think world history would have been very different had the Eastern Church dominated, and stayed unpolluted, and those two doctrines never adopted.
As far as the more modern, liberal churches, there was a time in 1700s & 1800s America where there was massive growth in this direction: Quakers, Unitarians, Spiritualism, etc.
But, with SCIENCE came Fundamentalism in response, and Biblical literalism – so 1800s and 1900s, new Christian churches were more CONSERVATIVE.