Unfortunately, I'm a sceptic - and I mean the 'unfortunately' part because I really do wish the world could be that way. My own experience, however, leads me to believe that tolerance of difference (especially in religious circles) is not high on many people's lists of behaviour or established patterns.
I was raised a Catholic and until the age of eleven I attended catholic school. One of those schools had alongside of it a protestant school - separated from us by a six foot high chain link fence, the nature of which seemed totally logical to us at the time.
This was the seventies (which doesn't seem very long ago until I do the math and scare myself!) and in those days we were taught by our family and teachers that protestants were (and every time I recall this it makes me shudder) somehow abnormal and even subnormal. We were expressly forbidden by our elders, betters and teachers to even speak to the protestant children on - literally - the other side of the fence. It seems ridiculous now of course - in fact worse than that, it seems appalling to me that such bigotry was being actively encouraged and fostered - and even indoctrinated. But that's how I was taught, and from the sources I still have in the catholic world, things haven't changed very much. Non catholics are somehow viewed (from the pulpit as well as among families) as a strange breed who for inexplicable reasons fail to follow the one true religion.
I've been acquainted with people from many different creeds and belief systems, and although I doubt that I've ever got into the religious question very deeply with many of them, I know from some of them that my experience, although perhaps a little more extreme than most, is not exactly unique. This does not bode well for the notion of religious tolerance.
Here's my take on the matter (and by the way I say this in awareness of the fact that it's just MY opinion):
Religious belief (and faith) is, by it's very nature, often tightly bound up within an individual's primary or secondary belief systems - in other words tied to beliefs about which we feel so strongly about, we would be prepared to defend them either with our lives or at least to the point of violence. These days of course, violence is rarely resorted to, largely because of all the rules that secular society has put into place for the maintenance of law and order. At an individual level, I think that disputes over such important issues are usually held at the verbal level (any further along the spectrum of conflict and response and the consequences become too great to make it worth our while). That, I believe, is why most of our disageements - thankfully - remain at the verbal or written level. And quite right too.
However (you knew a 'however' was coming didn't you?) I think that many of us become totally entrenched in an argument and feel unable to accept - or even entertain - a different opinion or perspective because we are so deeply attached to a religious doctrine.
Giving up on an accepted religious belief requires of us, I think, giving up on something of ourselves - perhaps something we have grown up with or something we have embraced in later life, but nevertheless letting go of a BIG part of who we consider ourselves to be. I know a little of which I speak - I've done it. It took me a number of years to admit to myself that I could no longer fool myself that my old beliefs fitted with my experience of my life and the world at large. Even faced with the intellectual certaintly that my old beliefs simply made no sense in the factual world within which I exist, the old programs from my childhood hung in there, perhaps the most persistent being that letting go of my beliefs would result in eternal damnation.
These days I often describe myself as 'free' from my old beliefs. I use the word very deliberately. I am free - but convincing you of my beliefs is neither necessary nor warranted, and I don't wish to go into the details of my beliefs any further in this post (although I am very happy to respond to questions). My freedom is from limited thinking, from strict rules upon what I may or may not accept or even listen to. This means that I don't feel that I have anyone or anything looking over my shoulder when I speak or listen about ANYTHING. I can listen to a muslim, a buddhist or a christian, I can have a conversation with any of them and only have my own perspective to relate to. The most antagonistic thing I really have to say is that I disagree. It actually strikes me that not agreeing is not an antagonistic position at all, but religious people I know do seem to feel very challenged by this simplest expression of my personal beliefs.
I've done the zealous atheist thing too - I've wandered around feeling very motivated to make other people realise the folly of their beliefs in the supernatural - but I'm relieved to say that it lasted only a few months until it dawned on me that I was doing exactly the same thing as I had done as a follower of christianity. During that time I was as intolerant of other's beliefs as anyone else has been - and it was a very silly place for me to be, and I am ashamed of it.
For me, tolerance means being able to listen to or to read or otherwise observe another belief system, to recognize it as a personal matter for the believer and to not feel angered, insulted or challenged by the mere existence of that belief. I know that my upbringing taught me the opposite. I know that my early adult life was not lived in a spirit of tolerance, and I know that my views were at least broadly shared by most of the people I met. I also know that according to my beliefs of today, I was simply wrong to live my life in that terribly limited and limiting way. I have no doubt that the way I lived my life not only offended others but harmed myself as well as people I came into contact with, professionally or otherwise.
I worry that the world is largely comprised of people with similar approaches to their lives; namely sticking to their beliefs no matter what, intransigent and afraid to allow anything different into their minds, and willing to fight - or at the very least send young people off to fight on their behalf - in order to preserve a way of life that is more comfortable and familiar to them than actually ethically or morally sound.
There have been lots of people among us preaching tolerance, and they've been out here for a long time; yet still we see the world's major and most lasting conflicts based around religious labels. In a world like this, how does tolerance grow?