The Republican coalition of religious conservatives and business has its origins in the Civil War, where northern industry joined forces with fundamentalist Christians who opposed slavery. A quarter of all union soldiers were immigrants, mostly poor German immigrants. Iowa sent more volunteers (per capita) to fight for the union than any other state. What motivated all those people to fight and die in a war between British people? They had no personal stake in the war—they didn’t have industry powered by southern resources like cotton, nor were any battles fought anywhere near their homes. For them, fighting for the union was about vindicating a religious opposition to slavery.
It was the confederates that portrayed themselves as being on the side of “science” against religious “zealots.” https://www.battlefields.org/learn/primary-sources/cornersto.... To make sense of that, put yourself in 1861. That was more than a century before we had the technology to determine that humans are genetically all the same. If you were someone who looked at the world—what people had built in Africa and what they had built in Europe—and said “these people are all the same,” that was a statement of faith.