Either way... I think you're statement is obviously false - there is less variation within christianity (caveat LDS) than there is between christianity and islam.
It's obviously true, until you carve out LDS for no reason n particular. What makes them "not Christian", other than a desire tomportray Christianity as not diverse?
Your own stipulation, which I accepted:
And of course, within Christianity there are not ENTIRE BOOKS about the Latter Day Saints that other parts of Christianity don't mention at all, right?
That's the reason, and it's not "no particular". It's a very particular reason, which you advanced.
...as a response to
your claim that ENTIRE BOOKS were the defining feature of religions that (unlike Christianity) are very diverse.
You are mistaken - unless you make the No True Christian argument that eliminates the LDS from Christianity. Indeed, you are mistaken even with that caveat unless you also consider Roman Catholicism "not real Christianity". Which many Protestant sects do.
Ultimately though, all the Abrahamic religions are very diverse, and most play the same game of claiming other sects as "us" when estimating how much political influence their opinions ought to have; But as "them" when assessing whose opinions to put forward.
"I represent the views and votes of a billion Christians", they say, "so the leaders of democratic nations should prohibit liquor sales". But they don't mention that alcohol prohibition is
not supported by the vast majority of that billion - most of whom don't interpret temperance as a message of the Bible.
Islam is similarly fractured. A Muslim co-worker once came with me to a football match, after I was given corporate box tickets by a supplier. Food and drink were laid on, and I remember Ali standing with a (free) beer in each hand, rejecting the sandwiches because the waitress couldn't guarantee that they contained no pork.
I asked if be wasn't also prohibited from alcohol consumption, and he said "My wife says that I shouldn't get drunk, and I tell her '
God has told me the same thing, and I don't pay attention to him, so why would I pay attention to you?'".
The point being that belivers areall individuals, and mostly cherry-pick; And that Muslims are no less diverse than Christians in that regard.
The existence of fundy nutbars who want to impose strict religious beliefs on everybody, with severe punishments for transgressors, is not particular to Islam, nor is Islam particularly prone to it. If you are concerned that some loony might wind back women's rights, and you live in the USA, then you would be crazy to focus that concern on Islam, while ignoring the clear and present threat of Christianity.
And if you think that all, or even most, Muslims are fundy nutbars, then you are simply misinformed - there are very few such idiots in any religion. But they are generally vocal, often oddly popular with their more moderate co-religionists, and always keen to claim far more support than they actually weild.