ObjectiveTruth:
Regarding Matthew 23:2 I posted some comments here.
Regarding Revelation 18:4 -
Like you, I agree that "Babylon the Great" represents a religious entity. On the other hand, I don't believe it includes "Christendom."
My reasoning is thus (And these are MY reasons. Others may or may not agree with me. But I don't want to accidentally hijack your topic or get it off topic.):
- Christ's rulership begins shortly after he ascends back to heaven, not in 1914. (See sub links here for what I consider Biblical evidence.)
- I believe Revelation to be written late 1st century. But how late is not important for this discussion.
- I believe the message of Revelation is relevant for all Christians from that time (1st century) until Christ returns (which is still future).
With those points in mind, what I believe about Revelation 18:1-4 is that "Babylon the Great" represents all of the religions that held sway over the Gentiles. Prior to Christianity, true worship was centered in Israel with a wall, as it were, seperating the true worship from the worship practiced by the Gentiles. (See Ephesians 2:14) Then, with Christ's sacrifice and resurrection successfully accomplished, Chrstianity becomes the true religion and it begins "invading" the Gentile domains. It was in this way that 'Babylon the Great had fallen' in Revelation 18:2 (Notice past tense in Rev. 18:2.) The way for Gentiles to become free of those religious organizations and worship the God of the Bible (as Christians) had been accomplished (without having to go to Israel under the Law). This formed the prophetic parallel of Cyrus taking the city of Babylon making way for the release of the Jews held there.
Revelation 18:4 ("get out of her my people") represents a call to Gentiles to take the opportunity to become Christians before "Babylon the Great's" demise, which hasn't happened yet. In effect, it parallels Matthew 24:31, where Jesus describes his intention to gather all his people from the ends of the earth. (See my post here for additional explanation of Mt 24:31.)
With this historical perspective, "Babylon the Great" could not include "Christendom." At the time of Revelation's writing there was no vast system of Christianity with its various sects. So the angel telling the words of Revelation 18:4 to John could not have been referring to the churches (regardless of how one views JWs or the churches in relation to the rest of Christianity).
When the "great earthquake" of Revelation 16:18 occurs, all of Christianity is dealt with first in the phrase, "And the great city was split into three parts." (Revelation 16:19a; See discussion on this post and here for additional. And see here for additional on how I see all of Revelation 16:19 fulfilled)
I tried to be as succinct as possible while still addressing your questions. With "Babylon the Great" representing non-Christian religions, it would make moot any question concerning leaving the JWs for another Christian religion (or visa versa). Rather, leaving Christianity, or [re]joining a non-Christian religion would be significant in connection with Revelation 18:4.
Take Care