The people knew what it is was to receive mercy from the hand of God. God will never bring judgement if anyone turns away from evil and truly repents of their sins. It is no different today. God still has people that He is sending out to warn of the impending danger that is about to come upon this world. People are still being warned to accept Jesus into their lives and many are not listening.
We must take every opportunity to warn all that we come in contact with today that time will not go on forever. One day, maybe even today, Jesus could come back and take His faithful ones home. We need to tell people how much He loves them and that they should take a lesson from the people of Ninevah. We need to do all we can to get the gospel of Jesus Christ out. Do all you can right where you are. God will bless your efforts. Time is quickly running out.