A universe with a God would look quite different from a universe without one. A physics, a biology where there is a God is bound to look different. So the most basic claims of religion are scientific. Religion is a scientific theory. ↗
The universe we observe has precisely the properties we should expect if there is, at bottom, no design, no purpose, no evil, no good, nothing but blind, pitiless indifference. ↗
For the first half of geological time our ancestors were bacteria. Most creatures still are bacteria, and each one of our trillions of cells is a colony of bacteria. ↗
I suppose if you look back to your early childhood you accept everything people tell you, and that includes a heavy dose of irrationality - you're told about tooth fairies and Father Christmas and things. ↗