The FF were very clear, and you are ridiculous. Historically noted care was taken with the language used in our country's founding documents. They were clear that they believed that *GOD* was important, perhaps even central, to good governance, but were excruciatingly circumspect in not noting which *GOD* or what religion.
They weren't unaware of other world religions. They could have built Christianity into the foundation, but they chose to distinguish between religion and spirituality in their language. The United States of America is not a Christian nation, and insisting it is shows you're far less tolerant than the actual patriots who fought for and founded our country.