What does 2 Thessalonians 2:11 mean?

In this verse Paul explains what happens to those who refuse the truth during the tribulation. He references an impending spiritual rebellion, and the rise of a powerful spiritual figure, the man of lawlessness. To those who are not Christians, God sends a strong delusion, so they will succumb to the false teaching of the man of lawlessness. A rejection of truth always predisposes sinners to accept error (Romans 1:18–23). In this case, unbelievers choose to reject the truth but believe the lie that the man of lawlessness is the Messiah.

Paul's teaching in this passage raises an interesting question: how does the truth reach the lost in the tribulation? Based on his prior words, Christians will not be present to share the truth. They will be in heaven, having been raptured and taken from the earth (1 Thessalonians 4:13–17). According to Scripture, however, God will raise up other witnesses to the truth in the tribulation. From the tribes of Israel, 144,000 Jews will believe on Jesus and evangelize the lost. Further, two faithful witnesses will preach for three and one-half years, authenticating their ministry by withholding rain from the earth and striking the earth with plagues. These witnesses will be martyred, but after three and one-half days, God will raise them from the dead.

The fact that so many living in the tribulation refuse to believe in spite of such powerful witnesses shows how hard the human heart can be.