Political candidates have one point - to be elected. If you’re anti religious - you won’t get elected in this day and age it’s just about as simple as that.
The use of “in god we trust” on currency historically has been nothing more than cheap shot propaganda to differentiate yourself from the “bad guys”. Coins during the civil war and currency changed to it during the cold war replacing the old motto “Out of many - one”.
It’s pretty much unconstitutional but no politician will ever dare to propose to get rid of “god” somewhere. It might as well be a political suicide.