It is often said that we must respect the religious beliefs of others. Simply put, I don't. That is not to say that I see religious people as less deserving of equal protection, but I do not see their beliefs as fundamentally reasonable and worthy of respect, and I think that this claim that we must respect the rights of others undermines our ability to have substantive debates on moral and political issues, by treating certain ideas as immune from debate and criticism. Why, as an atheist, should I respect those who believe, on religious conviction, that atheists should be put to death? Should I not show them the same amount of respect they show me?
The evidence in favor of most religions is weak or nonexistent. I focus on the religions I am most familiar with, but I have reason to believe that other religions have the same general flaws, as these flaws appear to be intrinsic to religion and not simply features of a few specific religions. One key flaw in religion is reliance on faith. Faith is belief without, or in spite of, evidence. Christianity treats faith as a key virtue, and denounces non-believers. It is repeatedly stated in the New Testament that those who do not believe in Jesus as their savior are bound for hell. The Old Testament repeatedly sanctions the killing of non-believers, as well as those who disobey any of a large number of commandments, such as by working on the Sabbath, disrespecting their parents, or even planting two different crops in the same field. Christians often dismiss the more draconian elements of their religion but fail to see that selective reading undermines their arguments. I am, of course, more comfortable around these cafeteria Christians than around someone who actually believes that people ought to be killed for working on the Sabbath, but I still see their position as intellectually indefensible.
Christians who invoke faith generally argue that the evidence is somehow inconclusive. A famous example of the approach that treats the evidence as inconclusive yet demanding our assent is Pascal's wager. Pascal posited that our only choices are to believe or not to believe (the agnostic stance of not taking a position is effectively treated as non-belief). Pascal tells us that if Christianity is true, then we have everything to gain (heaven) by believing and everything to lose (hell) by not believing. On the other hand, if it is not, then we simply die, and Christians will have at least led a good life. Pascal's wager might make sense if the evidence were genuinely inconclusive, though even in this case some problems arise.
First, his claim that we are better off believing Christianity, even if there is no afterlife, is unfounded. Christianity demands many things of its followers, including some fairly unreasonable demands. People who genuinely believe that they are bound for heaven may be better off, though their ability to reason properly is undermined by wishful thinking about the afterlife. However, even if belief individually makes people happier, rigid commitment to Christianity undermines pursuit of worthwhile goals such as scientific discovery. Scientific progress, including such real world benefits as discovering ways to cure or prevent fatal diseases, comes only by rejecting faith and considering the evidence on its merits. When faith is encoded into law, truth becomes heresy. It is not a historical accident that Galileo was subject to house arrest for life. The Bible teaches explicitly that the earth is immovable. The Old Testament says "Thou shalt not suffer a witch to live." (Exodus, 22:18) Most people now accept that there is no such thing as witchcraft, but many innocent people died because this biblical commandment was taken literally.
It is not even clear that we are individually better off believing. Belief that one is bound for heaven may ease the fear of death, but do Christians really not at least entertain the possibility that they will go to hell? Even if you are convinced that you are going to heaven, you may worry that loved ones are not. Hell is meant to be scary. It is a threat meant to keep people in line. What of the alternative? There are numerous other religions, which undermines the dichotomy of Pascal's wager, but suppose we treat atheism as the relevant alternative. Epicurus said "Death is nothing to us, since when we are, death has not come, and when death has come, we are not." I think most people are unable to grasp his point, perhaps because we cannot conceive of nothingness, and perhaps because the idea of an afterlife is so ingrained in us that what we envision is not true nothingness but some zombie-like state. It is not comforting to think, for instance, that I shall never again see my dead father, but neither is the atheistic conception of death something to dread. (I am not sure whether Epicurus was actually an atheist in the modern sense.)
Lastly, the evidence is not as inconclusive as Pascal suggests. First, absence of evidence sometimes is evidence of absence. When there is no reason to think that we would have evidence of something, then the logical stance is agnosticism. We genuinely do not know if there are advanced alien civilizations out there. The extreme distances involved make communication, let alone interstellar travel, very impractical. Radio signals are simply not detectable at even a few light-years, and the energy required for interstellar travel is nearly impossible to obtain. The number of stars is vast, but it is entirely possible that the barriers to achieving a civilization as advanced as ours, let alone one capable of interstellar travel, are so high that civilizations such as those imagined in science fiction simply do not exist. However, the most reasonable thing to say is that we do not know. We do not even have the information that would allow us to assign a probability to the possibility of encountering advanced alien civilizations.
However, a God like the one described in the Bible would leave copious evidence. It is absurd to think that Joshua made the sun and the moon stand still in the sky for several hours, and even more absurd to think that ancient astronomers around the world somehow failed to notice. Even if we are willing to suspend the laws of nature enough to allow for Biblical miracles, many of them are of such scale that they could not have gone unnoticed. If every ancient civilization recorded that the sun and the moon stood still as recounted in the Book of Joshua, and they seemed to be in rough agreement on details such as when this happened and how long the sun stood still, this would be compelling evidence that this event really happened. However, this event would be so extraordinary that the absence of such accounts is compelling evidence, as if any were needed, that it did not happen. Numerous impossible events are recounted in the Bible. Even fundamentalist Christians reject many of the moral teachings found in the Bible. For them to assert that this book is divinely inspired, let alone literally true, is intolerable presumption. We do not owe them our respect simply because they are religious. Their teachings are not uncertain or even improbable but provably false. Pascal's wager is refuted because we can and do know that Christianity is false. Those who claim otherwise are forced into logical contortions to avoid acknowledging the obvious. If they really do believe, then they are delusional, brainwashed, or engaged in sustained and pervasive wishful thinking.
So why does anyone regard such beliefs as worthy of respect? One reason is tradition. Another is that we find it difficult to really accept that so many people can be so fundamentally wrong. We can accept that old scientific beliefs were in error, and that ours almost certainly are as well. It is harder to accept that a large portion of the population is deeply and profoundly irrational. However, the evidence is compelling that this is in fact true. Nonbelievers, though, should not be content in our conviction that we are the rational majority.
Just because you do not share the same superstitions and logical fallacies as the majority does not mean that you are rational, but only that you do not share the same irrationality as the others. Many atheists were once believers, and some atheists become believers. Many atheists simply lack religious belief, rather than having actively rejected it as I have. Some reject religion for reasons no more rational than the reasons that others accept it. Some atheists have diagnosed or diagnosable mental illnesses. Atheists are not immune from groupthink or wishful thinking. Similarly, religious people may be very intelligent and their faith may not be so strong and pervasive that it has destroyed their ability to engage in critical reasoning.
The world may be better off if people voluntarily abandon their religious belief, but it would not be better to forcibly convert people to atheism. Religious tolerance has served us well. It has kept the peace. Atheists benefit from non-discrimination laws and would do well to comply with them and promote religious freedom. But religious freedom and tolerance does not require treating religion with kid gloves. You can, and should, respect a person's right to hold beliefs that you consider ridiculous. It is possible to regard a person as fundamentally irrational but still a person worthy of respect. A person who is good for the wrong reasons is nevertheless good. Furthermore, I do not believe that anyone is truly rational. Maybe there is some super-intelligent alien race of truly rational beings, but they are not us. The most intelligent people are vulnerable to addiction, self-deception and other irrational tendencies. Human sexuality is not rational. All of us have irrational fears and irrational desires. Aristotle said that rationality is what makes us human. What a privileged existence he must have had. If you are willing to consider that you might be wrong, then you have taken the important first step toward becoming a wiser and better person. If not, then why should I respect you?