Believing is like accepting and eating a stranger's casserole. Hopefully whoever made it had good intentions and was honest. You trust they didn't use feces as an ingredient.
Thinking is like knowing exactly what went into making the casserole, and how it was put together and cooked. You might have even made it yourself from ingredients you chose and combined, then cooked.
Making your own casserole is no guarantee that you didn't use a contaminated ingredient, or undercook it. But, at least any problems can be traced back to the source: you.
I am not comfortable believing but vastly prefer thinking.