 You believe that there was a man named Jonah who got eaten by a whale and then came back out, or a giant wooden boat with two of every animal. Look, in a materialistic worldview, miracles make no sense. If you only believe what you can taste, touch, sense, grasp, test, you will forever reject the claims of the Bible. But you're also forced to reject concepts of other non-material things, like the laws of logic and truth and love. Those things you cannot grasp with your hands, but you know they exist. This testifies to the fact that there is something beyond the natural world, something supernatural. God, the miracles in the Bible may seem unbelievable, but if you're someone who believes that something came from nothing, and from that primordial ooze we evolved over billions of years into where we are today, you're not averse to the idea of believing unbelievable stories.