I think you can safely say: The faith of our founding fathers. No JWs, Scientologists, "Christian Science," LDS, Wiccans, New Agers, self-improvement types, etc. among them. (And they didn't do so bad in the founding of this country, did they?)
Can’t argue with what you say but as far as I know, Thomas Jefferson was a Deist as were some of the other Founding Fathers and thus, not a member of any organized Religion.
What about Deists?