Question: "[A Missionary said] 'When a christian sins God requires him/her to repent (be sorry) and ask His forgiveness. He will forgive your sin'. No wonder sin is prevalent on earth. Now tell me, If I kill your child, then I go to steal, I slap you for no reason. In all these instances I become sorry and ask for His forgiveness and continue this cycle till I die I will not be punished? Even disbelievers too feel sorry for some wrongs they do."
Answer: Imagine you find yourself in court with a $50,000 fine. Will the judge let you go simply because you say you’re sorry and you won’t commit the crime again? Of course not. You should be sorry for breaking the law and, of course, you shouldn’t commit the crime again. But only when someone pays your $50,000 fine will you be free from the demands of the law. God will not forgive a sinner on the basis that he is sorry. Of course we should be sorry for sin—we have a conscience to tell us that adultery, rape, lust, murder, hatred, lying, stealing, etc., are wrong. And of course we shouldn’t sin again.
God will only release us from the demands for eternal justice on the basis that someone else paid our fine. Two thousand years ago, Jesus Christ died on the cross to pay for the sins of the world. His words on the cross were, "It is finished!" In other words, the debt has been paid in full. All who repent and trust in Him receive forgiveness of sins. Their case is dismissed on the basis of His suffering death. [From the Evidence Bible]
"In Him we have redemption through His blood, the forgiveness of our trespasses, according to the riches of His grace." (Ephesians 1:7)
"For the sorrow that is according to the will of God produces a repentance without regret, leading to salvation, but the sorrow of the world produces death." (2 Corinthians 7:10)