And the fact is that you have yet to show a clear teaching of the post trib rapture. The Bible simply does not state when this event will occur. ALL positions on its timing are based on interpretations of scripture. But almost every argument I have ever seen for the post trib position is based on the erroneous assumption that our Lord is only returning one time.
You have no biblical basis for saying that the Lord returning only one time is
erroneous. You have decided it has to be, but the fact of the matter is, the Bible doesn't teach it.
Acts 3:19-21
19 Repent therefore and be converted, that your sins may be blotted out, so that times of refreshing may come from the presence of the Lord, 20 and that He may send Jesus Christ, who was preached to you before, 21
whom heaven must receive until the times of restoration of all things, which God has spoken by the mouth of all His holy prophets since the world began.
Peter, in his first sermon after he was filled by the Holy Spirit, said that Christ will remain in heaven until the times of restoration. I assure you that before or during the Tribulation is not a time of restoration. Conversely, it is a time of destruction (Isaiah 24). Restoration comes when the Tribulation is over and Jesus returns (Matthew 24:29-31) and reigns on the earth, ridding the earth of those who hate Him (Luke 19:27, Zechariah 14:12-15, Revelation 11:11-15) while bringing peace and healing to the survivors of the nations (Isaiah 2, Isaiah 11, Isaiah 65, Ezekiel 47, Zechariah 14:16-20, Revelation 11:15-18).
Hebrews 10:27-28
27 And as it is appointed for men to die once, but after this the judgment, 28 so Christ was offered once to bear the sins of many. To those who eagerly wait for Him
He will appear a second time, apart from sin, for salvation.
The first time He came to be a sin offering. His appearing is post-tribulational (Matthew 24:29-30). This would have been a great place in Scripture to add a third time, if there was one.