I probably shouldn't bother, but-

America was founded by a bunch of Christians, and some of the country's construction surely was influenced by that.

However America was NOT founded as a Christian state.

Where the left & right butt heads over this is usually when, for example, pro-lifers say "God clearly forbids abortion and America is a Christian state so our laws must follow the Bible", and pro-choicers say "Uh, no, this is not a Christian state, the Bible does not set our laws".