Short version
It's hard-wired to followers of Abraham-based religions (ie. Christianity, Judaism, Islam) but Islam is the villain because they aren't white

Long version
Christians been doing this throughout the history, old habit dies hard. Christians been wandering around, put the sword to people throat (later on, guns, cannons & a piece of paper) & force them to convert for almost 2000 years now, what can you expect from these warlike people? The Catholics got the divine comedy that stated all non Christians will go to hell. But whatever, the Muslims also said the same thing but as said, you think they're the bad guy because they aren't white so I say racism also play some roles. Also, keep in mind Christianity once used as a mean to conquer Europe during the dark age, back then Christians are terrible terrible people who love to bash other religions & spark riots to burn down cities & slaughter non Christians.

It also has to do on the teachings telling you to beg & rely yourself to this man who died on the cross because that person "died for our sins" because that person is god & god love us so much to send a fraction of the deity to die here just to revive again in 3 days because the deity loves all of us & this death is to die for our sins. Because that this deity "died" it cleanses us somehow & we have to be grateful & rely ourselves with the deity in order to get to heaven.

That doesn't make any sense at all!!!

It also has to do with the fact Christians love to brainwash their children with stuff from the religion to the point all they can ever think about the world will be based on the book. That makes their children ignorant, arrogant & close minded. When these children grew up, the cycle continues & this is the product. Nut Islam also do this, but you think they're the villain because they aren't white

My country achieved religious peace even before Columbus discovered America, but the main reason is because the dominant religion isn't Christianity, go figure!

I don't feel that that is so much a matter of religion as it is of ego. In these matters, it is expressed through a religious context. What I mean is that people are so determined that they are absolutely correct in some thing or idea that the thought that some other alternative could possibly be true is alien to them. You can see this just as well if you ever take up a political discussion.

Also, to answer your question, my personal opinion is that there is no point whatever in disrespecting another person's beliefs. The fact of the matter is that no matter how fervently you may disagree with another person's spiritual beliefs, they will never have a direct effect on you one way or the other. If they choose to believe something that you don't, and it turns out they were wrong, well, they were wrong. Doesn't effect you. If it turns out they were right and you were wrong, well, you were wrong, and that is your own fault and not thiers. It's a wash.

I used to ask myself that a lot too, but I think I'm starting to understand it now. In some religions it's required to not get along with everyone, even if there's a rule somewhere stating that people have to get along anyway. Take Christianity for example. Yes, it's true, as a Christian you're supposed to love everyone, no matter what, in as divine a way as you possibly can. However, you can't just NOT tell someone they're not going to hell because according to you, that would be a lie. In some cases, but not all, it's not that Christians hate or intolerant of other people, cultures, and faiths, it's just that their faith insists on being true and as a result: they can't accept other religions as true ones.

While it sounds like Christians are breaking their own rules and judging people, condemning them to hell for whatever reason, in some instances it's not. They're just stating what they believe to be true, because it's very hard to put it any other way. The more nicer you try to make it, the more false it becomes. You can't just go, "Oh, whatever floats your boat, it's your religion," because in your faith there is no other religion.

In some people's religion you are told you have to go out and spread the word of God and point out their Gods are obviously fake and faulty. So for some people it's a religious requirement to not get along.

They believe they're right, and have the need to tell everyone else in order to "help" them understand, so everyone can be as "right" as them. It's not that complicated.

I tolerate people no matter what they believe in, and I have nothing against people who are truly striving to be better people through their beliefs/lack of thereof. But the moment someone uses that to harm me or my family, tell me I'm going to hell because I tolerate gay people, or rip the world apart with hate and prejudice I just don't have it in me to stay quiet. You should be allowed to voice you beliefs. But if voicing them includes yelling "CONVERT THE HEATHENS" or "GOD HATES FAGS," then I certainly don't think people like that are deserving of any level of personal respect.

Well, since most religions are basically an elaborate self-delusion, it must be carefully maintained. Logic and reason go right out the window; they'll bring your little world of willful-ignorance crashing down around you, if you let them. Further, seeing people with different, equally unsubstantiated delusions must put a hairline fracture in your rose-tinted glasses. Is everyone deluded, or just everyone else? The religious insist on the latter, and to avoid these harmful lines of enlightening thought, they seek to immerse themselves completely in their own delusion, hence their lust for conversion.

Also, Richard Dawkins, ever the evolutionary biologist, proposed another system. He stated that every individual aspect of a culture, which he called a "meme" (from which the Internet slang term is derived, I think), is subject to a sort of social natural selection, much the same way as organisms. Those memes which are designed to proliferate themselves, like religions that demand conversion from others, tend to proliferate, and thus are more successful than "respectful" religions. This explains why Christianity and Islam have such sweeping popularity; their adherents have striven for it.

Is it considered an insult to say that i don't agree with a religion?
Is your view of tolerance is to shut up about religion completely and just keep it private?
Tolerance is one thing, acceptance is another...

Acceptance cannot begin until we learn about and understand others and why their view is different. I can say i hate milk and people would not be offended because they will ask me why and understand. I can say i hate Christianity, and suddenly, i deserve to die burn for all eternity