Re George R and post trib
The entire point of the events of Revelation and the “great tribulation” is to offer a last chance to turn to God. There is a bride of Christ. I cannot think of a single example of an acceptable biblical bride which has been abused in kind with revelation judgments. Perhaps I have overlooked one.
A simple solution to your concern is that people do come to faith during this time.
Your definition of the tribulation is simply incorrect. No offense intended. First, the apostles already indicated that “tribulation” was being experienced in their time. It has continued since; the price of the availability of the Holy Spirit. Secondly, the “Mystery of God” is very clearly defined in the Gospels by Jesus himself. After His first parable is recorded, He explains that the “Mystery” is His gift of understanding to the apostles and their work. Their work is to build the church. These people are those in whom the Holy Spirit will dwell. The age of Grace is the “Mystery of God” and will end upon the completion of the verse you quoted, Rev 10:7. By most readings of Revelation this is far from the end.
It seems odd to consider that Israel is a protected woman, but the bride of Christ is left to slaughter. Oh well, if you want to stick around…?