Is America a Christian nation? Like much of everything else it depends on one's point of view; from the perspective of governance or that of the society in general.
Everson v Ewing BOE is one of the first SCOTUS cases firmly stating that governance, at all levels in this nation, are and must be secular. This is the law of the land and will remain so unless the Constitution itself is scrapped. In this regard this nation is most certainly not a christian nation.
As for the greater society the data show that the majority of the population in this society subscribe to some christian denomination. By this perspective this nation can be perceived as a christian nation. Note, however, that these christian beliefs appear, for a large part, to be tepid at best within the majority and are due mainly to acculturation, ascribed to more for social comfort than due to any strong personal religious belief.
And with the accelerating increase in “unaffiliated” identifications we can expect that within this next century Christians, indeed all religionists, will find themselves in the minority in this soon to be secular society.
As for McLeroy and his hoard of anti-American zealots, believe it or not, even in Texas, the organs of rational society will keep his dreams of theocracy unfulfilled. But don't let that fact be widely spread. McLeroy, et al, perform a vital service to the nation by keeping us ever fearful and vigilant against his poison.
Having lived in Texas for 20+ years I understand the problem. "They" are indeed everywhere.
But then there are also the ACLU - Texas, the North Texas Church of Free Thought, The First Amendment Institute of Dallas, Cato Institute Austin, The Flower Mound Rationals and a lot of people like you everywhere as well.