I'll start with a definition from my own tradition (Alma 32:21):
faith is not to have a perfect knowledge of things; therefore if ye have faith ye hope for things which are not seen, which are true.
So what is the justification for believing something that's not "seen"? (Here, I assume that things which are "seen" means things which are measurable via the standard senses and/or scientific instruments.)
Here are some possible justifications for believing a given proposition:
- Spiritual/Miraculous Witness: "I have experienced spiritual or miraculous manifestations that defy natural explanation."
- Hope or Leap-of-Faith: "I'm totally sure that X is true, however I think X deserves the benefit of the doubt, so I believe X."
- Unintentional Bias: "I want X to be true, and my bias prevents me from approaching the question with any kind of even-handedness or objectivity."
- Wilful Dishonesty: "I want X to be true, and I feel justified in believing whatever I want because I'm sure that everyone else is biased or dishonest too."
Now, the whole point of my earlier post (and its predecessor) was that options #3 and #4 are not "faith". If you are a person of faith, and you think that either #3 or #4 is a reasonable description of how "faith" works, then you should do a little introspection and perhaps hold yourself up to a higher standard of honesty. And when you accuse atheists of having "faith" of varieties #3 and #4 above, you are not paying your own faith a compliment.
Now how does atheism [lack of belief in God(s)] fit into the above four categories?
Atheists are all over the map, so they can potentially fall into any of them:
- Spiritual/Miraculous Witness: This is the one atheists are most likely to reject, yet there do exist people who believe in the supernatural without believing in God(s).
- Hope or Leap-of-Faith: There are perhaps a few atheists here, but I think most atheists fall into a related category which I'll call category 5. Weighing Naturalistic Evidence: "I'm not 100% certain that X is correct, however, I have examined the evidence, and of all the possibilities, I think X is the most likely." (That's pretty much how science works in general.)
- Unintentional Bias: Atheists are only human, so some of them almost certainly fall into this category. (I'm not claiming 100% certainty here though! ;^) )
- Wilful Dishonesty: As with #3, there are probably some here too.
Note that's it's also possible to consider a question even-handedly and still make an honest mistake. That can account for some of the disagreement in the world.
Also, IMHO, category 4 (I want X to be true, and I feel justified in believing whatever I want because I'm sure that everyone else is biased or dishonest too) is the one that is truly repugnant. All the others are either right or potentially honest mistakes.
I think that it's probably impossible for humans to overcome (or even recognize) all of their biases 100%. However, there is a very big difference between honestly trying to compensate for your biases and deliberately not trying.
It's like what I said about racism: It is probably impossible for humans to completely avoid mentally grouping people into stereotyped "other" categories. But that's not an excuse to throw in the towel. Addressing your own biases and prejudices is a lifelong effort. But it's a necessary and worthwhile effort -- that is, if you're curious about the universe, the world, and the people in it.