You would have to be completely ignorant of any of the actual founders writings to make a statement that claimed that the US was not founded on Christianity. They (the founders) made it completely clear in their many writings their opinions of how vital Christianity was to our freedoms and our ability to hold them in the future.
One can only assume you have not dug deeper or more than likely, seeing you devotion to islam, like to propagandize picking and choosing in order to deceive.
I rarely use Jefferson as a strong source. He was always writing "thoughts" not necessarily "truths". Madison is a better source.
We can agree or disagree, but it serves no purpose to make unfounded accusations.