I think a big problem with the American mindset is that most assume there are: 1) Christians 2) Muslims 3) Jews and 4) "Other" And a complete lack of recognition that each of those first 3 categories has an infinite number of subcategories, in addition to a ton of syncretisation with other faiths.
There are large regions of the US where "Catholic" is seen as distinct from "Christian". Even just among Baptists, there's a lot of variation. Which is how we ended up with Jimmy Carter leaving the Southern Baptists.
"There are large regions of the US where "Catholic" is seen as distinct from "Christian". As a Brit, this is so weird to me.
As an Irish-American from Boston, this is weird to me, too. But it's a big country.
We got taught a sort of taxonomy? Religion: Christianity, Hinduism, Sikhism, etc Abrahamic: Islam, Judaism, Christianity "Jesus was a real historical dude": Islam, Christianity Christians: Catholics, Protestants, etc. So Catholics/Protestants are Christians like dogs and cats are both carnivora
(I do realize "real historical dude" carries different implications when one group says he's a prophet and the other he is the son of God/part of the Trinity - and there's surely a nonreligious group who say he was just a nice fella. But there's that commonality of "he actually lived at that time")
It was a much bigger deal before Kennedy, and Italians were considered integrated. It's still seen as a divide in the South, given that so few Catholics down there are white. That said, while Americans are aware of some Christian differences, it is totally oblivious to nuances in other religions.
Much of my master's thesis focused on the Sephardic community in Istanbul and the factors that drove them to leave in the early 20th century. People always ask, "Were they Zionists?" and it's like... that wasn't really on their mind at all. They had their own life experiences driving them.
People are not monoliths. It is such a contrived Western concept that anyone can check off just one box to define themselves.