Personally, I feel like widespread religious tolerance is always going to have an uphill battle to face given the very nature of religious belief.

See, it's easier to adopt a pluralistic "live and let live" attitude about things that are personal, subjective, or just unique to your particular culture. When it comes to cultural differences in food, art, fashion, social customs, etc, people have an easier time being tolerant because the stakes just aren't as high and "the other" is not a direct threat. In those examples, the mere existence of another form of cultural expression doesn't completely negate or cancel out your own, so it's a little easier to coexist.

Whereas monotheistic religion is, for the most part, a zero sum game. They're designed to cancel each other out. Which is why it's rare that a "true believer" of a major religion is going to think, "Sure, this happens to be my little belief system, but who's to say what's actually true? Maybe that other religion over there is correct and mine is completely false." Obviously there ARE many who think that way, but those people are not the "true believers." They are the doubters, the skeptics, the wavering believers. Or they're simply very humble, open-minded people who have decided to soften and minimize the absolutism of their own religions, essentially deciding that their own private reasoning can supersede the actual doctrines of their religion. But for the "true believer," this God is 100% objectively real, every bit as real as this keyboard and this wooden desk right here, and so is every last word of his doctrine. If you truly see the universe this way, there's no way you're gonna shrug your shoulders and be like "Maybe those other religions are just as good as mine." So I would argue that the very notion of equality and coexistence among the major religions is antithetical to their inherent design and would completely invalidate their authority and their claims to objective, universal truth. They can't ALL be right, and I think any religious believer who argues otherwise can only do so by standing in direct opposition to their religion (which many people do, of course, and I have a lot of respect for that).