People who are ardent critics of the Bible like to sarcastically compare faith in the contents of the Bible to believing in a “flying spaghetti monster”. Their point is that much of the Bible is not scientifically provable or falsifiable. In their mind, that equates to being mythical or not real. Much about the materialistic explanation of the world has not been proven either, and it is all but mathematically falsified; but that doesn’t seem to make scientific theory untruthful in their minds. To the skeptic, the Bible is mythical because it is old (written by ignorant people in antiquity) and some of it has that “mythical” sound to it.
Even some church bodies (who shall go unnamed here) have given in to cultural pressures and have declared some parts of the Bible to be myths, even though Jesus seems to treat them as factual. They argue the Jesus used fictional stories (parables) to teach, so why couldn’t God do the same in the Old Testament. The problem with this approach is that there is no internal reasons to interpret the Bible this way. It leaves open the door to write the whole thing off as a myth, which people do.
The Bible records fantastic, unprecedented events because they are unprecedented. The virgin birth, the miracles of Jesus, the resurrection of Jesus and the events of the Day of Pentecost are times where God intervened in the history of the world in ways that defied the laws of physics. Their historicity is settled by the quality of their eyewitnesses and by prophetic anticipation. You cannot go back and repeat the event or find direct archeological evidence, but that is the case for most of accepted history.
So what about the Creation story, the tower of Babel, the flood, the Exodus and Jonah and whale? These seem even more mythical? The first three are even removed in time from the writer, so there are no eye witnesses. Why should we believe them? I start with Jesus. Did he regard the story or the book that contained the story to be historical? I have to say “yes” in each case.
Which would leave any evidence? The flood and the Exodus could. Signs of water covering every portion of our current land mass do exist, but geologists interpret this in the light of gradual, observable processes. This method became the established orthodoxy of geology since Charles Lyell. Still, we observe cataclysmic processes at work in the universe, and if God is involved, perhaps uniformitarianism is not the truth of how water got everywhere. As far as the Exodus is concerned, chariot wheels have been found under the Red Sea. What else would you expect to find?
It is not necessary for salvation that a person believe that every story in the Bible is historical, but everyone needs to ask why they doubt its historicity. Bible stories don’t lack all evidence like a flying spaghetti monster does. Some go against the accepted scientific interpretation of evidence. Keep in mind that those interpretations start with the assumption that God doesn’t exist. Formed that way, they will never prove that He does. They will only produce theories, some of which are so mathematically unlikely, that they are miraculous in their own right.