I view religion as a symptom of humanity's inability to operate as a rational agent. This statement will usually validate itself by being misinterpreted as an attack on religion, despite the statement itself simply stating that religion is irrational, not that it is a bad thing. Furthermore, we don't know if irrationality is inherently bad or worse than rationality, although humanity in general seems to prefer thinking of itself as rational despite repeatedly acting in completely irrational ways, usually without knowing it.
Almost everyone nowadays has grown up with the advice that everyone is special. Most kids figured out around junior high that if everyone is special, no one is special, and some get all depressed over it (like I did). This is logically inconsistent if one examines people in terms of their unique perspectives. Every person on earth has a wholly unique outlook on life, and this is why a crowd of people will often have at least one person who can quickly and intuitively answer a question that stumps the rest of them. Their unique perspective allows them to arrive at a conclusion much faster and more accurately than the others, and so it is this perspective that makes everyone unique. This is also why perspectives are valuable: the more diverse a collection of perspectives, the more likely that one of them will figure out the solution to a given problem. This is especially important to society at large, because society by definition must confront an endless stream of problems from every imaginable background, including some backgrounds we don't have names for yet.
The value of unique perspectives is exemplified by the Geth, a fictional race in the world of Mass Effect. Even though they were willing to destroy the Heretics for choosing a path that made it impossible for co-existence, they were reluctant to simply rewrite them so they would see their point of view because this resulted in a loss of perspective. In addition, the Geth opposed using borrowed technology because it would blind them to alternative paths. These different perspectives and possible solutions are what the Geth see as valuable. Even a perspective that is clearly wrong could potentially be valuable - the only time a perspective's destruction can be justified is if the perspective calls for the destruction of other perspectives, which makes it incompatible with society.
On the other hand, teenage hormones also kick in during Junior High, solidifying the desire to fit in with other people, which is in direct conflict with the desire to be different and unique. The end result is that humans tend to fit in with certain social groups, and try to be different from others. These social groups meld perspectives together, so that the general result is that each social group will have its own general perspective on life that it strives to keep different from other social groups, where individual perspectives tend to meld themselves to be closer to the group. While the potential loss of unique perspectives is unfortunate, as long as there are many social groups, the end result is a diverse population of perspectives in society.
Religions, however, attempt to enforce very similar "bubbles" of perspective, which can grow very large. Monotheism, usually in the form of Christianity, is extremely common in the western world, and is so common in the United States that it has created an enormous bubble of very similar perspectives. To apply the laws of economics to the situation, Christianity is a monopoly on the capitalism of perspectives. Whereas the ideal scenario is a lot of small bubbles of perspectives "competing" with each other, a monopoly makes it much more difficult for smaller, radically different perspectives to gain hold, and actively attempts to make itself larger in any way possible. Just as a monopoly is considered a serious problem in a capitalistic economy, so is a religious monopoly on perspectives.
Some more tolerant views of religion hold that an individual should be free to worship God in whatever way they wish, so long as they are worshiping God. This has two problems, the first being that it often excludes polytheistic religions, but primarily because it always excludes atheism. Theists who believe that atheists are to be tolerated, but would prefer that they didn't exist, are eliminating a perspective.
Consequently, atheists who simply tolerate religion are also eliminating a perspective. The simple fact is that both atheism and theism should always coexist so long as they are compatible with society and other perspectives. This means that the only rational opinion that one can have for religion is that it should be maintained as an entirely personal choice of perspective, and consequently valued as such. Of course, rationality itself is a perspective, so it would be more accurate to say that this is the only possible perspective that does not eliminate other perspectives (unless you can prove that one of the perspectives is sufficiently detrimental to society as a whole). The most valid perspectives, in general, are ones that tolerate other perspectives. Contact is on of my favorite movies, and it does a superb job of illustrating how both science and religion must coexist, and that it would be difficult for either to exist without the other. Science gives us technology, and religion gives us the faith that drives us to believe in potential discoveries before we have any actual evidence to believe them.
Differences in opinions are not problems, they are the manifestations of our unique perspective that make everyone valuable to society. Provided, of course, you aren't screaming "DEATH TO THE INFIDELS", because then you are trying to eliminate someone else's perspective to the detriment of society. Because of this delicate balance between perspectives, it is up to society to decide which perspectives are too much of a danger to others. In doing so, however, we must always remember that Islam is not a single perspective, it is 1.5 billion perspectives.