Please don't allow anything to distract me from Your message, dear Lord. Amen
"And for this reason God will send them strong delusion, that they should believe the lie, that they all may be condemned who did not believe the truth but had pleasure in unrighteousness." (Revelation 2:11-12)
Some people will come to know the Lord Jesus Christ during the Tribulation. But the Bible doesn't say this will be true of any person who has heard the Gospel and rejected it prior to the Rapture.
In fact, it says God will allow those who choose sinfulness over truth to have their way. He will leave them to the consequences of their choice and will even help them to stay on their chosen path of destruction. If a person goes into the Tribulation after willfully rejecting the Gospel of Christ, God will see to it that they believe the Antichrist's lies.
Remember, satan's superman won't appear to be menacing but will be charming and persuasive like his father, the master deceiver. Think of satan's subtlety back in the Garden of Eden. He didn't tempt Eve to fall down, but to rise up! He whispered that she could be like Gd, which doesn't sound like a bad thing, does it? So we see his craftiness even then - and he's been honing his skills for centuries. All his seductive, duplicitous power will be embodied in the antichrist (2 Thess. 2:9). And his deceptions will be tailor-made for those whose hearts already prefer their own wickedness to the love of God's truth (v. 10).
These are the people stubbornly refusing to repent, even in the face of God's mighty judgments (Revelation 16:9, 11, 21). They have become haters of the truth who instead embrace satan's age-old lie that God is not loving and forgiving, but cruel and unfair. And they will go to hell shaking their fists at the God Who did not want them to perish (2 Peter 3:9).
Perhaps you know someone who thinks they'll wait to make a decision for Christ. Warn them that the Bible says today - right now - is the day of salvation (2 Corinthians 6:2). If they wait until the great day of God's wrath, it will be too late for them.