I thought Scripture teaches the Rapture can't happen until the apostasy comes first and the man of lawlessness is revealed. So how can you say that the Church will be gone before the beginning of Tribulation?
Your interpretation of the Bible is in error. The Bible never connects the Rapture to the coming apostasy or the arrival of the Antichrist (i.e., the man of lawlessness). On the contrary, the Bible consistently teaches that the Lord’s return to His Church is imminent and dependent on nothing:
We believe you are misunderstanding Paul's teaching taken from 2Thessalonians 2:
Paul says that the “day of the Lord” cannot come to pass "unless the apostasy comes first, and the man of lawlessness is revealed.” The term “day of the Lord” is a reference to the seven-year Tribulation, not to the Rapture.