There are a number of different issues percolating around this question.
First, the context of the times was that the "norm" around the time of the Revolution was Christian, and overwhelmingly Protestant (with the exception of Maryland which had a strong Catholic presence courtesy of the Calverts). Congregational in New England, Presbyterian in the Middle Atlantic, and Anglican in the South, with a scattering of Anabaptists, Mennonites, Dunkers, and other small sects. An unbeliever or "infidel" was ostracized by most communities.
Among the upper class and college educated (the class from which the Founding Fathers and Signers largely hailed) the philosophy of the Enlightenment encouraged speculation and Freethinking. But this was primarily philosophical and not religious. Jefferson was roundly criticized for his rejection of parts of the Bible (something that the "biblical scholars" do all the time these days) and his doubts on the divinity of Christ. His enemies openly attacked him as an atheist. And my own great great great grandfather created a minor scandal by being a Freethinker in the 1860s!
The other thing you have to consider is that when many of the Founders appear to be attacking the Church from our point of view, what they are actually attacking is the Established church, that is to say an official government church supported by taxes levied on all the people, believers or not. Many founders objected to this on the principle of religious freedom, not because they necessarily agreed with the Nonconformists from a doctrinal standpoint. We haven't had an Established Church in so long that we've completely forgotten that issue, which was VERY hot at the time.
If you will research them you will find MOST of them were Christians. You don't have atheists having a 3 hour prayer to start the conventions and Congress if they didn't believe.
Just as an example... Benjamin Rush (who started 3 universities that are still around today) said that the reason to have public schools is so they can learn to read so they will be able to read the Bible. He insisted we use the Bible as textbooks.
Noah Webster... when he make his dictionary used Bible verses to give examples for the words. 27% of his words used Bible verses. The fly leafs had verses printed on them so as not to waste space.
You need to learn YOUR history. Please!
You might find it beneficial to read some original source materials...I cannot imagine non-Christians writing what some of the founders and framers of the Constitution wrote. In fact, the following is attribited to Ben Franklin, often considered to have been a Deist:
In beginning of the contest with Britain, when we were sensible of danger, we had daily prayers in this room for the divine protection. Our prayers, Sir, were heardand they were graciously answered. I have lived, Sir, a long time; and the longer I live, the more convincing proofs I see of this truth, that God governs in the affairs of men. And if a sparrow cannot fall to the ground without his notice, is it probable that an empire can rise without his aid? We have been assured, Sir, in the sacred writings that except the Lord build the house, they labor in vain that build it. I firmly believe this; and I also believe that, without his concurring aid, we shall succeed in this political building no better than the builders of Babel
I suggest a google search and some research is in order for you. Unless you prefer to sound like a robotron.
I suggest you try history books. Unless you prefer to be a robotron. Are you a product of public schools?
Life is bigger than one page excerpts written by a billion nobodys. In fact our nation was founded by Christians, and you can count the anti-Christians on one hand. Try the federalist papers or any History book written before the 1960s.
For an interesting experiment, then read a history book from todays classes as dessert. You will find it quite interesting how much history has changed in the last 50 years
(Concept, history is not what you make of it) Unless you prefer to be a robotron. My guess is you are a product of public schools?