The trouble with 'devout atheist' is that 'devout' directly pertains to religious belief. Describing someone as a devout atheist is really a fundamental misrepresentation of what atheism is - and instead brings it into the sphere of a belief system, which is a paradigm the religious are more familiar or comfortable with.
I think there are some logical flaws in your argument though, that simply because atheists don't believe in any gods, they shouldn't be able to or have an interest in pointing out the flaws or problems with some of what religions are saying, in a world where religions seek to impose their values, beliefs and practices on those who don't share them.
And we're back to secularism again, and why there are many secular people of faith. Because I'd have much less interest in pointing out why religions are wrong (including the one I used to belong to) if religions weren't seeking special treatment or privilege. If religions weren't seeking to affect my life, why would I or other atheists be really bothered?
That said, it would still be interesting from the standpoint of how humans tick - why religions spring up, why people follow them, the drives for the rise and current dominance of monotheism, etc. It's fascinating stuff.