In America, even the Catholics are Protestants.

If only the New Atheists were as honest as the Catholic Archbishop of Denver.

For their own purposes, a traditional New Atheist trope is to deny that the America was founded by Christians as a Christian nation.  They go so far as to cite to the obscure "Treaty of Tripoli" where some diplomats diplomatically pointed out that the American government was not framed as an explicitly Christian nation, and, so, had no dispute with Muslims on religions grounds.

But that doesn't deny that the nation was "born Christian" - or, more precisely, Protestant - or that the government didn't grow out of the roots of a particular Protestant ecclesiological practice that involved decentralized, federalized authority.

This is indisputable as Archbishop Chaput recognized in  a recent talk:

“The American model of religious liberty is rooted in the thought-world and idea-architecture of the Christian humanist tradition,” he said. “Whatever it becomes in the future, America was born Protestant.” The archbishop added that he was

not saying that our Protestant heritage is uniformly good. Some of the results clearly are good: America’s culture of personal opportunity; respect for the individual; a tradition of religious liberty and freedom of speech; and a reverence for the law. Other effects of Reformation theology have been less happy: radical individualism; revivalist politics; a Calvinist hunger for material success as proof of salvation; an ugly nativist and anti-Catholic streak; a tendency toward intellectual shallowness and disinterest in matters of creed; and a nearly religious, and sometimes dangerous, sense of national destiny and redemptive mission.

“The global situation is made worse by the inaction of our own national leadership in promoting to the world one of America's greatest qualities: religious freedom,” he said later in his address. “This is regrettable because we urgently need an honest discussion on the relationship between Islam and the assumptions of the modern democratic state. In diplomacy and in interreligious dialogue we need to encourage an Islamic public theology that is both faithful to Muslim traditions and also open to liberal norms. Shari'a law is not a solution. Christians living under shari'a uniformly experience it as offensive, discriminatory and a grave violation of their human dignity.”