Thank you for your detailed post. I disagree with your conclusion that the Great Tribulation and the Day of the Lord are not the same thing.
Can you give any scriptural support to the Day of the Lord being or coinciding with the Great Tribulation?
There are many which I think clearly delineate between the two. 2 Thessalonians 2 indicates that the anti-Christ has to be revealed BEFORE the Day of the Lord. His revealing appears to be at the abomination of desolation which is at the middle of Daniel’s seventieth week.
As I mentioned earlier, the signs in the heavens follow the Great Tribulation but precede the Day of the Lord.
During Daniel’s seventieth week, the anti-Christ exalts himself, especially beginning with the abomination of desolation.
But in Isaiah 2, it says that the Lord alone will be exalted in that day. Isaiah 2:10-21 is clearly alluded to by Revelation 6 as to what happens in the Day of the Lord.
There are two aspects of Christ’s coming — one in which we meet Him in the air, another in which He plants His feet on the Mount of Olives. There is one in which His angels gather the elect from the four winds, but another in which the angels gather the wicked to remove them.
The problem is that when Christ describes His return “immediately after” the Great Tribulation, He specifically links this to the signs in the heavens and the gathering of the elect. Where does this event happen in the Revelation?
In Revelation 6 and 7, there are signs in the heavens, the coming of God’s wrath, the sealing of elect Jews, and the arrival of believers in Heaven from all nations.
When do Jews turn to Christ? Isn’t it at His visible return? They shall look on Him whom they have pierced and mourn. (See Zechariah 12:10.)
If not then, when? When is the whole purpose of Daniel’s seventieth week fulfilled? When will transgressions cease and all Israel be saved? Will Israel remain in ignorance and unbelief right up until Christ returns with His armies and destroys anti-Christ? When will they look on Him and repent?
If Christ comes at the beginning of Revelation 6, where do these many believers come from who are beheaded for the word of God in 6:9-11?
When does God send people “strong delusion” as in 2 Thessalonians 2? If He sends strong delusion, where do all these believers come from?
There are many martyrs in 6:9-11, and then there are multitudes that “come out of Great Tribulation” in 7:14. How is this possible when God says He will send the strong delusion on those who did not receive the love of the truth? If the Church has been raptured out before all these things, who will preach the gospel to them so these people believe?
If they did not believe during the dispensation of God’s super-abounding grace, with God’s Spirit poured out and convicting mankind, with messengers sent out to reap the harvest; how will they repent when God has ended this era and the era of wrath has begun, with no messengers left to preach the Gospel?
God did not appoint us to wrath, but to obtain salvation. In this world we will have tribulation, but we are to be encouraged because Christ has overcome the world.