Religions exist because if they don't have a reason not to kill each other... they'll kill each other.

Religions (most of them) have a list of case where it is deemed acceptable to kill other people. So no, that's bullshit. Religions exist because 3000,2000,1000,500 years ago, humans lived in complete ignorance and superstition, if someone got a disease, there was no explanation, if there was an earthquake or a tornado, nobody could explain that phenomenon, so people came up with "the wrath of god(s)" and other bullshit. This and the fear of death and of course the existentialist question of the meaning of life. But there is absolutely no doubt that all the supernatural in the Torah, the Bible or the Quran were made up, angels don't exist, no more than Golems or Djinns, and no human has ever talked to god if he ever existed. Conveniently only a bunch of prophets did...

How many Christians, Muslims or Jews believe that Joseph Smith is legit? what's the difference between him and Mohammed, or Jesus, or Moses? There is none. What makes the latter more legit than the former? Nothing, it's all lies.