Those acts of God are fictional and maybe their God is fictional too. But, if literal, and their ancestors witnessed these things, as the Bible says, then they have a type of proof that God does reward them when they do good and obey. But brings punishments to them when they disobey. And I think that is the grander lesson of those stories. Obey... get rewarded. Disobey and get yourself smote. But then once a person starts taking all those stories as being fictional, why fear or even believe in that God?