Simple answer .... Truth! undeniable facts.

There are many things that science does not know, but the unknown is not filled with myth or legend. It is filled with the desire for knowledge.

Centuries ago we believed the earth was flat, but through science it was proved that was undeniably false. We once believed that the world was only 6 thousand years old, Darwin exposed this myth through years of meticulous study of evolution.

There are many undiscovered mysteries which great minds strive to discover, without resorting to a God as the solution for what we don't know, doing that is just a cop out and impedes research and forward thinking.

I'm sorry, but up to this day there is no empirical evidence for a the existence of a God

“It surprises me how disinterested we are today about things like physics, space, the universe and philosophy of our existence, our purpose, our final destination. Its a crazy world out there. Be curious, keep looking.”
Stephen Hawking