It's a tale as old as time, just like the Judean People's Front. Fucking splitters.

We have a very large christian population, and they all don't behave in a monolithic manner. For surveys it makes sense to ask which denomination or type of christian they are. Some will response Catholic, Baptist, Protestant. Some will respond christian, sometimes non-denominational christian. It improves the survey results. For example, you might find differences between Catholics and Baptists that wouldn't show up if you grouped them all together under a christian category.

Because it's not enough to argue with Muslims and atheists, they need to be more right than other people who believe in the same God in different ways.

It's a horrible graph. Likely they meant 'evangelical protestant' to differentiate that group from protestants like Lutherans Methodists Anglicans etc.

Oh American christianity is something different as a whole.

I'll give my best summary in as few words as I can during my lunch.

Christianity is an Abrahamic faith with its roots in catholicism. When Martin Luther, a catholic from Germany, wrote a large 95 point thesis detailing his problems with catholicism and how the church had been warped from its intention, this lead to whay most modern Americans would call Lutheranism.

This reformation of the church that started with Martin Luther is known as the Protestant Reformation, protestants being anyone who believed in Christ but not in the orthodox or catholic belief set and rites.

The separation of that faith and the pursuit to practice it openly (sometimes even if it was MORE restrictive than the existing systems) led to the exodus of religious groups to America. This is where some Americans get the idea that "america was founded on Christianity and religious freedom", as these were protestants who were escaping religious persecution for rejecting mainline catholicism.

Some time down the line, I don't know the history of this part, the general term for anyone believing in christ but not catholicism (some going as far as saying lutheranism is catholic-lite as they still practiced communion and most protestants don't recognize communion or any of the 'rites' as those are things they see as placed on top of religion by man and not by God) was just left at Christians.

For all intents and purposes, in the US, Christian mostly means Protestant, methodist, Lutheran, Baptist, Southern Baptist (they're separate, I was raised Southern Baptist, they get pissy about being lumped in), calvinist, and non-denominational (people who don't claim a 'branch' but worship christ in a way not easily or intentionally not tied to a singular rhetoric.

Please ask more questions and I'll try my best. Having been born to a Southern Baptist family, it's a topic I love to discuss and learn more on. I'm not religious though, so hopefully none of my stuff comes off disrespectful, just happens to be a family trade I can't quite put down.

Don't forget adventist, pentecostalism, lutheranism, etc. There's dozens of christians religions in the USA that may hate each others. This doesn’t make much sense.

Because they all seem to think their beliefs are the true beliefs of what the Bible teaches. They will always be at war with one another.

The “teachings” of the Bible are all based on how one person interprets it compared to another, the individual churches all believe the same version as they were taught by their religious leaders, who in turn believe their ultimate religious leader, for example the Catholic Church (all variations) follow the pope and his interpretation.

https://www.youtube.com/watch?v=l3fAcxcxoZ8