I have no problem admitting that there are several things I can't do. Dance, sing, crochet, play soccer or roller skate, just to mention a few. That doesn't bother me at all (that there are things I don't master), but it does bother me when a person decides to rub it in my face. What does that mean? That you stand above me? I almost feel bullied, even though it sometimes isn't meant that way, but in rather in a jokingly type of way.
Not everyone can sing and dance, and certainly not everyone understand the way an engine works. It's plain disrespectful to look down on someone because he/she can't do a certain thing. It doesn't mean that that person is anything less than you.
I also experience the feeling that I'm not as "important" because I don't have a God. I don't believe that there is a special power up there, and therefore I'm looked down on because of that. Doesn't the Golden Rule say that you should "do to others what you would like to be done to you"? If these people who claim they have faith and respect to their religion, why don't they follow this rule?
The fact that I'm an atheist doesn't mean that I don't have any moral or values. I don't visit the church and eat meat - does that make me anything less "a good human"?
(Hm, I sort of went a little bit off-topic there, I think...)