When science gets mistaken for just another kind of faith
The reason they'd call science our "religion" is very similar to why the word "atheist" exists : it's because we do not have a religion, therefore it must be called a "non-religion" and a "non-religion" has got to be just like a religion. Obvious, right?! Poor Aristotle must be turning over in his grave. If everyone is a sports fan and you're not, does that make you something? Of course it doesn't, but whenever there's a majority doing something, one will feel tempted to assign a qualificative to the minority that isn't doing it. It sounds like a way to justify the majority and make them think that we're forming "another team", playing their ridiculous game too. In fact, we're only just watching, although it does worry us when they make too much noise or when the result of their passion ends up affecting our own lives. Pushing the non-religious analogy a bit, if they start lobbying around and give us less opportunities to succeed in life because they dislike that we're not playing their game, then we have to somehow promote and defend our right to not be playing, even if it is ironic to the core. Looking up the definition of religion and the definition of science, we see that science is fundamentally different from religion. A religion is a set of beliefs concerning the cause, nature, and purpose of life and the universe; science is an enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the natural world. If they won't even read their dictionary, let them think what they want. But we won't allow them to deny any of our liberties simply because they're pissed that we don't share their passion for nonsense.
As Sam Harris said, however, religion is probably just failed science. If he's right, that would help explain why these two get so often and easily compared. Remember that with natural selection, it takes many, many unsuccessful attempts before something actually starts working right. For example, while the brain of a human baby is being formed, 10X the number of available connections have to be discarded because they just end up not having any use. What a waste! Not mentioning that our eyes are wired to the brain... backward...! If we really have a designer, that designer should have been fired a long time ago. He's such a slacker. What I really want to say is that, over tens of thousands of years, the same kind of "trial and error" process should have naturally happened with religion as well. As time passed, we had to build new models, or improve existing ones so that they could fit our new understanding of nature. Thousands of religions that could not adapt to these changes simply vanished. Such selective process also involved that a lot of energy would go to waste, creating relatively frequent regressions. In conclusion, we should not be too surprised at the current state of things; although I think it's safe to say that any religion will naturally disappear as soon as our understanding of the natural world has made it completely unfit to explain even a single thing. We've seen some religions disappear throughout history... and thanks to science, I'm confident that we'll see it again.