It doesn’t seem like this was always the case - obviously there’s a lot of myth making about the “founding fathers”, but it does seem that a lot of them were genuine Enlightenment men.
I’m not under any illusions that the USA was ever a secular nation, but it seems like the phenomenon we see now, of right wingers marrying America = Christianity, Christianity = America, in their worldview, wasn’t always there.
Is it just the result of Cold War propaganda, juxtaposing the American empire of Christendom with the evil atheist soviets?
Just look up the anti choice movement's origins.
THE NOT-SO-LOFTY ORIGINS OF THE EVANGELICAL PRO-LIFE MOVEMENT http://religiondispatches.org/the-not-so-lofty-origins-of-the-evangelical-pro-life-movement/
"Randall Balmer has succinctly put it: “the religious right of the late twentieth century organized to perpetuate racial discrimination.” Only after the movement was underway did it begin advocacy on abortion.
They have to go back to Roman theologian Tertullian to reinforce their claim that the “orthodox position” is that life begins at conception, conveniently leaving out the fact that Church fathers Augustine and Aquinas—and most evangelicals up until the 1970s—are on the other side of the argument.
Its founding moral outrage stemmed not from Roe v. Wade, but from the prospect of government-imposed desegregation; it rest its intellectual foundation on highly dubious, non-scholarly arguments advanced by Francis Schaeffer; it mobilized lay evangelicals to action by telling them the Bible teaches something it does not actually teach; and it actively suppressed the scholarship of evangelicals who held alternative viewpoints. The Bible, does not, in fact, teach that life begins at conception, evangelical scholars understandably emerged to challenge these views. The evangelical pro-life movement maintained momentum by actively suppressing such scholarship."
The ‘biblical view’ that’s younger than the Happy Meal https://www.patheos.com/blogs/slacktivist/2012/02/18/the-biblical-view-thats-younger-than-the-happy-meal/
"At some point between 1968 and 2012, the Bible began to say something different. That’s interesting. Even more interesting is how thoroughly the record has been rewritten. By the mid-1980s, the evangelical right was so successful with this strategy that the popular evangelical community would no longer tolerate any alternative position. By the time of the 1988 elections, everyone in American evangelicalism opposed legal abortion and everyone in American evangelicalism was pretending that this had always been the case."