At the link below is one of the clearest explanations (in text and video) of a Scriptural basis for believing that believers will be raptured before the Tribulation.
Revelation Chapter One
19 “Write, therefore, what you have seen, what is now and what will take place later.
These are the three divisions of the book that David Jeremiah outlines.
The things you have seen: What John just saw in chapter one and some introduction
The things that are: the next two chapters consisting of letters to the 7 churches in the Mediterranean region. They are letters not just to those churches but to us and Jesus takes the time to emphasize this saying for us to “listen to what the Spirit says to the churches.” We get the benefit of seeing the ups and downs of the church that came before and SHOULD learn from them.
The third chunk of Revelation is “the things that will take place after this” and goes from chapter 4 to the end, chapter 22. The church is not mentioned again as we know it because it’s been taken up in the Rapture and isn’t present for what happens on Earth in the tribulation.
10 They were looking intently up into the sky as he was going, when suddenly two men dressed in white stood beside them. 11 “Men of Galilee,” they said, “why do you stand here looking into the sky? This same Jesus, who has been taken from you into heaven, will come back in the same way you have seen him go into heaven.”
We live with the hope of His return
2 Thessalonians 1
5 All this is evidence that God’s judgment is right, and as a result you will be counted worthy of the kingdom of God, for which you are suffering. 6 God is just: He will pay back trouble to those who trouble you 7 and give relief to you who are troubled, and to us as well. This will happen when the Lord Jesus is revealed from heaven in blazing fire with his powerful angels. 8 He will punish those who do not know God and do not obey the gospel of our Lord Jesus. 9 They will be punished with everlasting destruction and shut out from the presence of the Lord and from the glory of his might 10 on the day he comes to be glorified in his holy people and to be marveled at among all those who have believed. This includes you, because you believed our testimony to you.
2 Timothy 4
4 In the presence of God and of Christ Jesus, who will judge the living and the dead, and in view of his appearing and his kingdom, I give you this charge:
Jesus will return as judge after the 7 year Tribulation
2 Thessalonians 2
9 The coming of the lawless one will be in accordance with how Satan works. He will use all sorts of displays of power through signs and wonders that serve the lie, 10 and all the ways that wickedness deceives those who are perishing. They perish because they refused to love the truth and so be saved. 11 For this reason God sends them a powerful delusion so that they will believe the lie 12 and so that all will be condemned who have not believed the truth but have delighted in wickedness.
POINT OF CORRECTION:
I had said that some will come to believe during Tribulation that had heard before but David Jeremiah says that those who come to believe will be those who had never heard before. Those who heard and rejected before will not get a second chance but will be under delusion so they continue in their unbelief. See 2 Thessalonians 2:11 above.
After this will come the Millennial reign of Jesus for 1,000 years. There will be righteousness from those believers who return with Jesus but still some unrighteousness from SOME of the children. Having the choice to believe or not some will reject.
The Great White Throne Judgement concludes the millennium and ushers in eternity.