A far higher percentage of people in our early history were religious than now. Many of them practiced at home because of the lack of churches and transportation issues. Back then, the parents took the role of spiritual leader in the home when church wasn't nearby or convenient. Just because these people weren't "churched" doesn't mean they weren't devout believers.
It's easy for a clever person to cook the books with figures and stats. I have zero doubt that the US has moved further away from God over the years.