> The world didn't used to be like that. I credit Christianity with the invention of proselytizing; religions before it (including Judaism, its immediate parent) were content to stay with a given tribe and not try to spread. It goes hand in hand with wars for religious conversion, which also weren't a thing before Christ. Today the same thing plays out with politics (I'm not just fashionably pointing at wokeness here, the wars for "democracy" have very much the same roots). The moment memes switched over from religion to politics as primary content seems to have been the French Revolution, I can't think of a time before that when people killed each other over political ideals.
Yeah, Christianity does seem to be the first religion that asserts it has universal good news that transcends national boundary, religious affiliation, race, etc. It is not the first religion to make universal claims, of course—Judaism asserts that Yahweh, for example, is the only true God—but it does appear to be the first religion that is specifically anti-tribe. In this sense, Christianity is incredibly inclusive. At the same time, Christianity appears as an incredibly exclusive religion, too: monotheism is nothing if not exclusive.
One might argue that the reason for its emphasis on proselytizing is two-fold: one, because adherents really did believe it was good news and naturally would spread it, and two, because it was a powerless religion. Once clearly distinguished from Judaism, it enjoyed none of the famous Roman tolerance for the other monotheistic religion and was sporadically persecuted until the time of Constantine.
The question of religion and war is an interesting one. Politics and religion were inseparable prior to Christianity, and it is hard to imagine a world in which they are separable without Christianity. The idea that you can separate Caesar from God stems from a famous interaction with...Jesus.[1] (Caesar is literal in the text, of course, but a metonym in later interpretation.) Of course it took a very long time for political theory to develop to the extent you could imagine a country in which church and state were separate. On the other hand, it's also hard to imagine a world in which you could plausibly go to war to convert someone to your religion without such inclusive claims as Christianity makes: war likely would have retained its religious underpinnings, of course, but wouldn't be characterized with evangelistic fervor.
Can you have one without the other? I'm not entirely sure. That is to say, I'm not sure we could have a society in which we could meaningfully separate church and state without simultaneously running the risk that we'd have religious war.
> For example, science doesn't try to make you into a spreader; it's content to have you do science.
Do you see a meaningful difference between "doing science" and "spreading science"? Do you have opinions about the phrase "believe the science"?
[1] See, e.g., https://www.biblegateway.com/passage/?search=Matthew+22%3A17...
It's germane to the conversation that the general tenor of the time, at least as recorded in the New Testament (see, i.a., https://www.biblegateway.com/passage/?search=Acts%201:6&vers...) was that God's Messiah would be a military ruler and re-establish Jewish dominance.