Agreed. You can’t force religion on someone that isn’t receptive. That doesn’t stop some people from trying.
Oh, sure. Some people raised as atheists do subsequently become religious.
Interestingly, though, the group most likely to adopt and retain the religious position of their parents is those raised as non-religious. Should we deduce that, of all parents, non-religious parents are the most effective at brainwashing their children into conformity? 
Could it be that these parents are not expecting/relying on a third party (the church/religion) to do some of the heavy lifting, and are therefore more successful because of this?
Of course non-religious parents are relying on third parties to do some of the heavy lifting. The thing is that the third parties in question are the physical universe and the educational systems that talk about said universe. Brainwashing your kid into believing that gravity exists is pretty darned easy with that kind of support system to back you up.
Well, it could. But we have no a priori reason to think that being supported in your childrearing efforts by third parties generally makes those efforts less successful. So some stronger theoretical underpinning, plus some well-thought-out research, would be required to evaluate this hypothesis. 
That is kinda what raising kids is all about. They ALL get inculcated into society and parents are a big part of that. Putting children in a cage and feeding them till they are 18 would not get good results.
I think the OP, rephrased a bit, would be what limits are there on what can parents do? Is there a limit to the craziness a parent can instill in their kids?
My WAG is parents have huge leeway here. There may be some limit but I cannot think of one beyond the state forcing them to provide basic care (hygiene, physical health, clothing, some kind of housing…maybe education).
I think the only recourse a child could have, if they disagreed with the parents, is to try and emancipate themselves from their parents (legally).
I think it is pretty rare but it does happen. That’s big and difficult step for a minor to take. Whether, “My parents are making me go to their church” is sufficient I do not know. I’m guessing no unless the “church” was doing things that were harmful and not just proselytizing.
The authority of parents to raise their children as they see fit, particularly when it comes to religion, is near-absolute, as long as they meet the educational requirements set by law in their state, and don’t physically abuse the children.
Even where educational requirements are not met, the state seems reluctant to intervene. We see this here in New York City in some of the Hasidic communities.
We see it in families where parents require that girls wear the hijab (lots of that in my neighborhood).
If the new family were adoptive parents, they have the power to try to change the child’s beliefs. They can require church attendance and prayer and study at home (or at least require that the child go through the motions of prayer).
Same situation. The parents can forbid church attendance. They can forbid the possession of a Bible or other religious books. They can proselytize (not exactly the right word, I guess, but I can’t think of a better one). It would be hard for them to forbid quiet mental prayer, of course.
I don’t like the direction this can go in sometimes – the separatist (for want of a better word) religions (like some Hasidic sects) are really unhealthy, in my opinion.
But what’s the alternative? State-sanctioned religious education? State bans on religious education? Putting aside any questions about constitutional law, does anyone seriously think those would be good things? Or even possible?
In a free country, parents will always have the right to raise their children as they see fit (with certain limits that have nothing to do with religion).
My background:
I was raised in a religious (Catholic) household. I attended Catholic schools through my first year of college (and, by the way, I distinctly remember evolution being taught as part of elementary school biology).
My children are receiving a religious education, although they attend public school.
I consider this my absolute duty. Isn’t it the duty of all parents to try to inculcate beliefs about ethics and morality? To socialize their children? In my case, that can’t be disentangled from religion, although I understand that other parents don’t share my beliefs, and I’m fine with that. But otherwise we’re just raising feral children.
Sorry, but how does being raised to wear a hijab get in the way of meeting educational requirements?
I don’t think it does. Sorry if my writing was confusing. I just meant it as an example of parents imposing religious beliefs on their children.
The kids don’t seem that happy about it, or at least some of them don’t, judging by how many girls I see putting on the hijab when they get within a few blocks of home.