I think that this is the bit of common ground that I have with your more conservative/fundamentalist/etc. types. Generally speaking, I find myself rolling my eyes a lot less when I speak to religious believers who tend to be open minded and less dogmatic. There is one thing though with many more liberally-minded folks that I often find frustrating, and that's this idea that beliefs don't matter. Of course, I never hear it put in quite those words. It's more along the lines of: "Hey, if it makes him feel good, then who cares what he believes?"
I also have heard (several times lately) the puzzling phrase that "it's true for them". The first time I heard this was when discussing religion with a Catholic, who said that she had a Muslim friend, and the Muslim's beliefs were "true for him" and her Catholic beliefs were "true" for her. I cannot for the life of me fathom what this means. Unless one means to propose a completely subjective universe, where reality is dictated by one's own perceptions and beliefs, then it strikes me as sounding rather nice but meaning very little. After all, Catholicism and Islam have conflicting ideologies. Either Mohammed was the last prophet or he wasn't (among other things). While they can both be wrong about who's a prophet and who isn't, they certainly can't both be right.
And yes, I am aware that when it comes to many Eastern religions/philosophies, the belief systems can be a bit more accommodating. This is why Buddhism didn't wipe out Shintoism in Japan, and you have some people, particularly in China, who follow Confucius, Taoism, and Buddhism. I'll let the experts in those subjects handle whether that's logically coherent or not, but I feel like I'm on firm ground when I say that if Islam is true, Christianity isn't. No eating all your cake and then claiming to still have it.
So, let's get past this whole notion that "true for you" only fits if we're talking things that are purely subjective like what the best flavor of ice cream is, not objective knowledge claims like who got the right message from the creator of the universe. If you're with me so far, then let's get back to this notion of whether we should care what people believe or not.
There are two major reasons why we should care what people believe, and they're linked together. The first is that my beliefs affect my actions, and the second is that my actions affect other people. Gay people in California wanted to get married and have all of the benefits that come with that. The citizens of California voted against them having that right, and so many couples who had been together for years, if not decades, couldn't enjoy the same privileges that I can with my wife. Now, whether you are for or against marriage equality, you cannot deny that people were effected by the beliefs of others. (Thankfully, it was overturned by the courts, and now gay people can get married here - but my example still stands.)
I understand the democratic, egalitarian motivation behind it when people talk about just letting people have their beliefs. (And let's be clear, I only advocate changing people's beliefs through dialogue and education - I don't believe it's either possible or ethical to force people to change their beliefs.) However, I think that it's a flawed idea. We don't all live in a vacuum. What we do affects others, and what we do is motivated by what we believe. In other words, beliefs DO matter, so let's stop pretending that they don't.
But hey, that's just my belief. If I'm wrong, tell me why - although you'll kind be proving my point if you think it's worth taking the time to convince me otherwise.