Most people can only believe when they see physical evidence. It is one of the reasons why some have a hard time believing in who Jesus is. But this is where faith comes in. In Matthew 16:4 Jesus said, A wicked and adulterous generation looks for a miraculous sign, but none will be given it except the sign of Jonah. Jesus then left them and went away. Jesus used Jonah as an example of resurrection since Jonah was swallowed by a fish for 3 days just as Jesus would later be resurrected after 3 days. Jesus gave the people around Him plenty of information and signs about who He was and what He would do. But without ears to hear and a heart that is willing to believe, they missed the truth, just as people still miss the truth today.