Depends on what you mean by a "secular nation". If it is the defintion actually demonstrated by the Founders - that no one group would be established, no group would have primacy, all groups have freedom to worship as they see fit, and the laws of the land, while being on a general Judeo-Christian foundation, would not be particular to any one sect - then yes, this country was founded as a secular nation.
It by "secular nation" you mean the view held by left-wingers, Communists, and a goodly share of faux-conservatives here on Free Republic - that religion is forbidden from the public square, religion must be kept only in the home and church, no candidate or elected official can or should operate from a "religious" position or worldview, otherwise they are "violating the separation of church and state" and "using a religious test, which we all know the Constitution forbids" - then no, the Founders had no such thing in mind, by their own words.
Great post - absolutely correct.
You are so right. We have a freedom of religion but not freedom from religion. That is what our Founding Fathers established!