So let's say you're not a Christian. Life is good! You are not sick, lonely, or sad. You probably think you don't NEED God. Well, listen to this:
Sometimes the Devil allows people to live a life free of trouble because he doesn't want them turning to God. Sin is almost like a jail cell except it's nice and comfy and there doesn't really seem to be any reason to leave. The doors are wide open, and your chance at eternal life is right in front of you. But one day, when time runs out, the cell doors slam shut and suddenly it's too late.