I don't think atheism among biologists (Which I am) has to do with fear of violating professional norms. It has to do with finding it difficult to place god in the context of evidence-based descriptions of life that is part of our profession. Or at least, the god of the religions that we grew up with is not consistent with the hypotheses that are standing up to test after test. Simply put, if you cut just about every organism down the middle and looked at them in cross-section, there is almost no diversity among living things on earth (Although they get squished into somewhat different shapes), which would be weird if they were all independently created.
Moreover, it is hard for us to accept that:
1) A god that makes unbreakable laws like gravity would make a bunch of arbitrary, breakable laws and tell one species on one planet never to break them or suffer forever, and
2) The same god would surround that species with millions of other species that violate every single one of those laws on a constant basis.
In general I see the Judeo-Christian philosophy (Humans were intended to rule the world) as a way of explaining our rise to power, and ultimately justifying it. But it places humans in a role that is isolating and self-destructive.
But I don't think that the number of scientists that are atheists is the same as the number that would say they are not spiritual at all. That number is probably low. We're not presumptuous enough to claim that we can explain the "Why" of the Universe.
I've been an atheist for as long as I can remember. I have had moments where I question if anything is out there, but it always comes back to science for me. It's hard for me to think abstractly, and I think that affects how I view spiritual ideas.
I went out with an atheist and he was so anti-God and religion, it was as if he made atheism into a religion by itself. As with any belief, I don't care what you believe in, just don't try and convert me. So if you don't believe, don't harp on about it, as if you are missing out.
Yes, atheists often held so strongly to their beliefs to become really similar to theists.
Personally, while I don't believe in god, I'm open to everything and am confident in people making their choices.
Of course, religion must not limit other people freedom!