Bharat,
We in the ACA are actively promoting atheism and church-state separation. Atheism in the US is rapidly growing and becoming more accepted.
Most atheists I know are champions of reason, evidence, scientific thinking, education, and doing what we can to tear down bad ideas. We have local groups, national groups, magazines, books, conferences and so on. It's most definitely a movement. While many of these are focused around atheism, many others are focused around skepticism, freethought, or humanism. I don't know that we're limiting ourselves, exactly. We are trying to focus on the few things that really matter.
As for stopping the theist from indoctrinating their kids, I think the only way we can do that is to change the popular culture so that fewer of them are indoctrinated. We can try to protect children with secular laws. That said, it's not the place of an advocate to step between a parent and their children.