Humans sin. It’s what we’re good at; we’re rock stars at doing the wrong thing.
The Philistines doubted that God could be greater than their gods – they challenged His sovereignty and control when they had the Ark. They were wrong.
Sometimes the Bible verses people point to to deal with fear aren’t all that helpful to me. First, there are the ones that tackle the issue head-on, like Isaiah 41:10, which says
How can a seed die, and still become a plant? How is it possible to die, and still be alive?
What you feed your mind dictates how it runs, and that, in turn, affects the manner in which you live your life.