> If Democrats held power for a couple of decades, the country would be unrecognizable. Take, for example, the issue of religion. Americans are the most religious developed country by far—comparable to Iran. This drives Democrats crazy, and through the period during which they controlled the Supreme Court based on FDR’s appointments, they turned America into one of the most secular countries in the world in terms of the law. European countries far less religious than the US have far more public accommodation for things like religious instruction in schools. Imagine going into Poland or Hungary and declaring that Christianity has to be removed from schools, like in France. It doesn’t matter what you think of these policies. What do you think the societal reaction would be to that?
This isn't factual. Italy for example is more religious than the US. Germany, France and the UK are comparable to the US (each have ~25-28% nonreligious, compared to 25% in the US). Poland, to use your example, is 85% Christian and 8% nonreligious. Hungary is 20% nonreligious, and close to 75% Christian (60% Catholic).
The comparatively religious countries are approximately as secular. The US isn't unique here.
Also, it's worth noting that the constitutions of Poland and Hungary establish national religions. The Polish constitution specifically protects religious education in public schools, and the Hungarian constitution defines life to begin at conception.
The US on the other hand doesn't have that. The establishment clause doesn't have those carve outs. And as to your claim that the FDR court made the US particularly secular, I don't see that. Public funding for religious education had already been well established to be unconstitutional (with the majority of states having banned it explicitly in the 1800s). It's difficult to tell how common religious education in the style of McCollum was during the early 20th century, but I can't find anything to suggest that it was the norm in public schools.
> If Democrats held power for a couple of decades, the country would be unrecognizable.
You haven't described what, in particular, Democrats would do. What anti-religion policy do you suggest democrats would do if they held power for several decades (and, presuming that democrats were able to hold power for several decades, would this be any different than other similarly secular nations?)
The best example I can think of requires conflating Abortion policy as anti-religion policy, which it isn't, in the same way that legalizing gay marriage isn't anti-religious.