The church being gone, does not mean there will be no tribulation for Christians. The church being gone means that in order for the anti-christ to rule, the church must be gone, and Christ proven FALSE. The AntiChrist will perform miracles, die and raise up, just as Christ, and because of this people will believe in this new “Religion” of the AntiChrist. And if there was going to be a PRE rapture, why does Christ consistently warn us not take the mark of the beast?
You’re correct. The Church being gone only means there will be no tribulation for the Church. Beginning in chapter 6, the Book of Revelation is a description of the 70th Week of Daniel. During that time there will be terrible judgments, including the Great Tribulation.
There will also be many converts to Christianity, but none of them will belong to the Church. The warning not to take the mark of the beast comes in Rev. 14:9-11, just after the beginning of the Great Tribulation and is for these post Church believers, not for the Church. Jesus never mentioned anything about taking the mark.