Question: "What does the Bible say about a death bed conversion?"
Answer: The most high-profile death bed / last-minute conversion to Christ in the Bible is the case of the criminal crucified alongside Jesus (Luke 23:39-43). Only moments before his own death, this criminal had been an unbelieving mocker of Christ (see Matthew 27:44). However, at the last moment the criminal repented and acknowledged Jesus as the heavenly King. The Lord gave him the blessed promise, "Today you shall be with Me in Paradise."
Although the story of the criminal on the cross demonstrates that last-minute conversions are possible, the Bible warns us to repent now, without waiting another moment. John the Baptist warned, "Repent, for the kingdom of heaven is at hand" (Matthew 3:2). Jesus had the identical message concerning the need for immediate repentance, "Repent, for the kingdom of heaven is at hand" (Matthew 4:17).
The Bible warns us concerning the brevity of the human lifespan. "You are just a vapor that appears for a little while and then vanishes away" (James 4:14). We are not instructed to consider converting someday, but to believe today! "Today if you hear his voice, do not harden your hearts" (Hebrews 3:7-8, 14; 4:7). None of us knows how much time we have left in this life or what the circumstances of our death will be. We may die in a sudden, unexpected manner that will preclude a deathbed conversion. The only reasonable option is to repent and believe in Jesus Christ today.
Many people die without having the experience of an extended amount of time on a death bed. Many people die instantly and unexpectedly, with no opportunity to trust in Christ. 2 Corinthians 6:2 declares, "In the time of my favor I heard you, and in the day of salvation I helped you. I tell you, now is the time of God's favor, now is the day of salvation."