I know plenty of people who are "religious" solely for the social contact. They couldn't tell you -- or probably care less -- what their church taught on any particular subject beyond common-knowledge Christianity. For them it's just the Sunday morning coffee klatch. And that's absolutely fine with me, since those are the people who seem least likely to do anything to which others might object.
However if, like me, you live in a state dominated by a particular religious sect, that sense of community has a dark side. Mormons express a tremendous sense of community, much of which has positive outcomes. But it's such a proportionally large community that non-Mormons easily feel like second-class citizens.
That's merely a social consequence, but here the community leaks over into things like employment, housing, social services, etc. that really need to be free from interference. At places I've worked, it's not uncommon to see employees at various levels of the company talking openly about church activities, participation, etc. to the extent you suspect that work and church are really just facets of the same community. This makes it hard to have confidence in employment-related decisions -- hiring, firing, promotions, etc. Though not universal, it happens often enough that firms would rather hire, and landlords would rather rent to, people "from within the faith." And while that's illegal, it's easy to get away with. And with our legislature currently in session, most relevant conversations revolve around what the Mormon church is going to say about each bill, which has historically correlated with whether the bill passes. There is widespread suspicion that some state legislators simply do what their church leaders say, though that's denied from both directions.. But it sure doesn't help that the capitol building is just a couple blocks away from Mormon HQ.
That's my particular experience living in a highly religious area. I've heard similar stories from other places in the U.S. where religion is dominant for social and community reasons as well. I wouldn't say this is the same everywhere I've lived.
My atheism comes from simply not believing in the religion. The religion doesn't have to "fail" per se in any colossal or embarrassing way for me to arrive at that decision. But in my case, where religion often flexes its muscles in ways I find inappropriate, I become a more active atheist. Which is to say, I oppose the inappropriate intrusion of religion, not for what is believed, but for what is done. You could probably chalk that up as a "theism fail," but I think it has more to do with ordinary community behavior. People can act like jerks without it being related to a belief in God.
The success of science doesn't really affect my atheism. I work with dozens upon dozens of scientists and other scientifically-minded people who are also active Mormons (and not jerks about it). Their theistic beliefs don't affect, or seem affected by, their ability to be good scientists. Granted the science we do doesn't really get into places where science and Mormonism would clash. But I think one's adoption of science and a scientific mode of thinking doesn't really necessitate some particular theistic or atheistic belief.
