There was a list of presidents who never clearly stated their denomination.
Thomas Jefferson
Abraham Lincoln
Andrew Johnson
George Washington was a mystery also. Some say Episcopalian and we also know he was a Mason.
Some say TJ may have been a deist.
As for Lincoln, I believe he was a Christian because of his thirst to study scripture and the wisdom he showed through understanding and fluent use. I don't thin he has a specific denominational allegiance but I also don't think it's necessary for eternal life.
There's a strong argument that Lincoln was never truly converted.
Even the strong pro-Lincoln historian Peter Marshall (junior) agrees that Lincoln was not a Christian until the third year in the White House.
And I thought Eisenhower also never joined any church. He might have at one time been considered of his parents' faith, but not as an adult, because their was one opposed to all war.
To many here on this board, yes...
They will say one can't be a Mason and a Christian also. However, the truth is many of our founding fathers were Mason's.
Whatever Jefferson was, he could not have been a Christian since he rejected all the miracles of Jesus. Didn't he tear out all the supernatural events in the NT and create the "Jefferson Bible?"
Most of the founding fathers were nowhere near similar to any form of a modern evangelical Christian.
Anyone who supposes otherwise is either ill-informed or willfully ignorant.
I didn't want to say it that way but I suspect you're fairly correct. There are so many on this board who believe we are a "Christian" nation founded on "Christian" principles by our founding fathers. I agree they used the words God and Creator a lot but I think they had a different understanding than we do today.