Some Bible interpreters believe that there will be absolutely no chance for salvation after the Rapture. However, there is no place in the Bible which says this or even hints to it.
There will be many people who come to Christ during the Tribulation. The 144,000 Jewish witnesses (Revelation 7:4) are Jewish believers. If no one can come to Christ during the Tribulation, then why are people being beheaded for their faith (Revelation 20:4)?
Another view is that those who hear the gospel and reject it before the Rapture cannot be saved. Those saved during the Tribulation, then, are those who had never heard the gospel before the Rapture. The “proof text” for this view is 2 Thessalonians 2:9-11, which says the Antichrist will work miracles to deceive “those who are perishing” and that God Himself will “send them a powerful delusion” to confirm them in their unbelief. The reason given is that “they refused to love the truth and so be saved” (verse 10). Granted, those who are hard-hearted toward the gospel before the Rapture are likely to remain so.
And the Antichrist will deceive many (Matthew 24:5). But “those who refused to love the truth” does not necessarily refer to people who heard the gospel before the Rapture. It could be anyone who wholly rejects God’s salvation, at any time. So, there is no clear scriptural evidence to support this view.
Revelation 6:9-11 speaks of those martyred during the Tribulation “because of the word of God, and because of the testimony which they had .” These martyrs will correctly interpret what they see during the Tribulation and will believe the gospel themselves and call on others to repent and believe as well.
The Antichrist and his followers will not tolerate their evangelism and will kill them. All of these martyrs are people who were alive before the Rapture, but who were not believers until afterward. Therefore, there must be opportunity to come to Christ in faith after the Rapture.