Well, I'm not sure of your thoughts regarding the "Great Tribulation," so I'll not foist anything on you, but merely give you mine. :)
1. I disagree with your understanding of Christ's Church, or at least what I think is your understanding of it. I say it consists of all those who are called by the Lord and thus in Christ.
2. Regarding a "Great Tribulation,"As sort of a preamble, consider some synonyms for 'tribulation' (some key synonyms noted with an asterisk... although they're all good):
- adversity
- grief *
- suffering *
- trial *
- heartache
- burden *
- trouble *
- misery
- oppression *
- misfortune
- ordeal
- woe *
- persecution *
- difficulty
- affliction *
- distress *
- sorrow *
We all are experiencing all these things to some degree... currently. And as long as there is sin and death in this world, there will be tribulation. Regarding a "Great Tribulation," I do see a great ramping up of the current tribulation near the end, such as will have never been seen up to that time. And it will be cut short for the sake of God's elect. No one living will be removed from it (whether you're insinuating that or not), but the Lord will be with us, His Church, through it, just as He promised He would be.
Grace and peace to you.