2 Thessalonians 2 (NKJV): 1 Now, brethren, concerning the coming of our Lord Jesus Christ and our gathering together to Him, we ask you, 2 not to be soon shaken in mind or troubled, either by spirit or by word or by letter, as if from us, as though the day of Christ had come. 3 Let no one deceive you by any means; for that Day will not come unless the falling away comes first, and the man of sin is revealed, the son of perdition, 4 who opposes and exalts himself above all that is called God or that is worshiped, so that he sits as God in the temple of God, showing himself that he is God. The antichrist comes first, and he causes the great tribulation, which then causes the falling away (apostacy). This great falling away from the church is the result of many pre-tribulation believers NOT being prepared in any way for the horrendous persecution that will be coming upon them! These many will NOT endure with their faith until the end of their lives. These many will NOT refuse to take the mark of the beast. Scriptures are available upon request regarding … the warnings that either one of these two causes loss of salvation! All of this happens before Jesus comes to rapture His bride (in verse 1).