Common sense and personal experience.
Not all people who go to church BELONG to a church. I don't, I am an atheist, but I have gone to many different churches over the course of my life to experience them and investigate their absurd claims. Most people in America, providing they are not of retirement age, have had ample years of factual educational scientific evidence disproving the possibility of anything remotely resembling a "god". It's a leap of logic only the severely retarded or severely isolated could make honestly.
Americans attend church for the lucrative business contacts (most males fall into this category), or a desperation to belong to something socially (most women), or the need to be considered "good" or "better" than others, but mainly in the end it's out of simple cowardice. They are terrified to buck the crowd mentality and possibly be ostracized for their views. I'd say maybe 10% of church-goers are ignorant enough to actually believe in the possibility of a god. The rest are liars and chickenshits.
A national lie detector test would reveal a only tiny % who actually believe in that fairy tale shit.
An end to all tax exemptions and subsidies for these private country clubs, which is what they really are, would easily balance the budget for our country.
God would want them to pay their way.