Comparisons between religion and atheism are typically more a matter of rhetoric than logic and a matter of emotion more than measured analysis. There is not a single assertion about religious or philosophical thought which will not offend someone. While I will do my best in this post to be fair and consistent, I am certain it will inevitably disturb. If that possibility is too much for you, please do not read what follows.
I am continually disappointed that people parade their own knowledge and their own experience as the pinnacle of absolute truth. I am thankfully not alone. There are both religious and non-religious people who agree with me that each person should express his or her own views in humility, taking caution to remember the limited perspective and knowledge of each human being.
People of many creeds and traditions have adopted and cultivated an active sense of doubt. While individuals often disagree on which things they doubt and which things they accept, there is a consensus that each person should doubt all opinions equally and persistently.
Some people who are not religious believe in doubt so strongly that they refuse to claim belief in any faith. Those who would undermine the supremacy of doubt as a value often reply that doubt itself is also a faith, as strong as any religion. This accusation begs the question of what constitutes a faith.
It is difficult to say with any certainty precisely what faith is, which is fitting, given the difficulty in providing any absolute definition of an individual faith, such as Christianity or Islam. I realize it is dangerous to claim that beliefs are a faith before I have discovered what makes something a faith. I must admit I already have assumptions about what makes a belief a faith.
For me, a faith begins as an idea. An idea is some sort of guess about the world, some kind of hunch. A belief is an idea that one accepts strongly, and I view faith as an even stronger form of belief. Doubt is definitely a belief, because it is a pervasive idea with an extremely high number of applications. I disagree, though, that doubt alone is a strong enough belief to be a faith.
When I was in a class called "Contemporary Political Thought" last semester, a friend of mine and I had a very similar argument. He claimed that "if you state that all truth is provisional, you have asserted an absolute truth, so you can't really say that everything is provisional because it self-contradicts". I responded by stating that if the idea that truth is provisional can itself be contradicted by evidence, then it is not an absolute claim. The test of absoluteness is not whether a belief claims that it applies universally, but whether it could be hypothetically overturned by evidence at some point and then no longer apply universally.
I believe that a faith is something that claims to apply universally, but cannot be demonstrated by evidence. A faith is a belief so strong that it cannot be falsified by evidence; it is beyond even contradiction or non-contradiction. No one can challenge it rationally. This distinction is why atheists will turn funny colors and foam at the mouth a little bit if you claim that atheism is a faith. Perhaps a very strong atheism is a faith - I agree that the non-existence of any supernatural or metaphysical presence cannot be falsified by evidence. However, a weaker atheism, which asserts that only as a condition of the lack of evidence for supernatural forces, that one should not accept supernatural forces, does seem entirely different from the concept of a faith, in that its conclusions are not so strong that they could never be challenged by direct evidence.
That so many religious people claim that "people of faith" are every bit as capable of doubt as non-religious people is fine. It's a valid claim. By definition, you can only doubt a belief that is falsifiable. I also believe, however, that it is worthy of debate whether a person should believe in something which no possible evidence can disprove. I do not have any problems with this sort of belief on principle, as long as its practitioners acknowledge that it is a belief beyond the bounds of rationality and non-rationality. When people use their religion to make scientific or historical claims, those claims entirely undermine the concept of faith. A religion underpinned by scientific or historical claims should not be recognized as a faith, but as an ideology.
And in practice, religious ideologies often use their untestable claims to support actions which damage and hurt peoples' lives, because the ideology claims absolute superiority for itself and does not act in humility, and does not recognize its own limited knowledge. Very strong atheism is one of these negative ideologies, and also harms people - I already accept this to be true. When people absolutely believe that religion is a negative force in the world, there is much good and positive benefit that is ignored.
It is important to state, however, that atheism and doubt are not necessarily a faith. If you wish to challenge atheism, please challenge it not with insults, but with a response to its claims. Just as it is not fair to insist that religion should be accepted unless it meets the standards of rationality, it is unfair to insist that atheism is necessarily a faith. By definition, it is true that faith is not necessarily about evidence, and that atheism is not necessarily a faith. When challenging an idea, one must first understand what the idea means, and then challenge the meaning of the idea as it is understood by those who accept it. Only once you have responded to the claims of an idea that it actually makes, should you pretend to have made a serious intellectual challenge!
Is there anything directly wrong with faith? Not necessarily. Sometimes, there are questions people have about meaning, about values, about things outside the boundaries of science, which are almost impossible to answer but demand an answer. Occasionally, there are questions which may never have one right answer that can be rationally confirmed. Perhaps some moral and ethical principles are a faith - but perhaps they are not a faith. Perhaps there is rational evidence available to ground our values and ethics. May we never know for sure? Certainly. That's why I'm not certain.