Is it fair for someone to live a really bad life and then get saved at the last minute while someone who was really good his whole life but doesn’t get converted to Jesus goes to Hell? That doesn’t seem right.
First of all, what people consider fair is not what God considers to be fair. The Bible tells us that God is holy (1 Peter 1:16), and holiness requires nothing less than self. Also, all people have sinned (Romans 3:23), and sin results in the judgment of God (Isaiah 59:2, Romans 6:23). Therefore, the person who lived a good life is still a sinner. Obviously, a "good person" has not sinned as much as a person who purposely rebelled against God his whole life. But it is not the amount of sin that is the issue. Rather, it is sin itself. Any sin is sufficient to bring damnation.
Second, the sacrifice of Jesus (who was God in flesh, John 1:1, 14, Colossians 2:9) is of such tremendous value that it can clean the sins of someone who sinned only a little sin as well as someone who sinned a great deal.
So, is it fair that a person who was bad his whole life gets to go to Heaven because he accepts Jesus, but a good person who doesn't receive Jesus goes to Hell? Yes, it is fair. Whether someone has sinned a great deal or a little or receives Christ early in life or late in life, salvation is guaranteed to those who truly receive Christ as their Savior . . . all of their sins are removed. Without the cleansing sacrifice of Christ on the cross (which is received by faith), nobody will be able to stand before the infinitely holy presence of God, no matter how good they were on earth.