The sin of unforgiveness puts many people on the path to hell. If God can forgive you for your deepest darkest sins why can’t you forgive others for the smallest things? You repent and ask God to forgive you, but you can’t do the same. The things people don’t want to forgive others for are things they have done themselves. When you hold on to things in your heart it creates bitterness and hate. God does stop listening to prayers because of unforgiveness.