Taken from the comments, slightly modified to make it general rather than a reply.
The literal meaning of the term “indoctrination” indicates the matter at issue quite clearly. Here’s a very standard definition from Dictionary.com: “to instruct in a doctrine, principle, ideology, etc.” Children are not merely instructed in doctrine, of course, they are also inducted into the ranks of religious organizations in various ways: not just educationally, but socially, ritually, and so on. Moreover, inducting children into the ranks of their chosen religion is the explicit primary purpose of most parents who emphasize their children’s religious education, which is what makes it indoctrination rather than mere education: The word “education,” when unmodified, is generally used to indicate instruction in knowledge and skills, not instruction in doctrine or ideology. Using a term like “religious education” – which I also used – doesn’t change a thing about either the purpose or results of the process.
Which leads me back to my main argument: Children’s membership in religious organizations is by definition not voluntary because children (at least young children) cannot legally, morally, or psychologically be judged capable of informed consent. The assertion that parents have the right to pass their religious beliefs on to their children is entirely irrelevant, because I have granted that exact same right. But acknowledging parents’ right to raise their children in their religious tradition does have the inevitable consequence that membership in religious organizations has a very large, elephant-in-the-room-sized non-voluntary component. I’ll grant that many of the things parents make children do are not voluntary by this standard, including ordinary education – but involuntarily imposing membership in religious organizations on children has different consequences from involuntarily imposing vaccinations or school attendance or violin lessons or whatever. Why? Because religious organizations frequently violate basic principles of justice and equality.
I also granted that religious liberty deserves special protection, and that this protection could even extend to letting religious organizations violate basic principles of justice and equality within their ranks. But for any religious organization’s freedom to discriminate within its ranks to be consistent with a free society’s protection of all rights for all citizens – this is, for it not to unduly privilege religious freedom above other basic rights, nor to unduly privilege some citizens above others simply because they were fortunate that their parents happened to have raised them outside of any discriminatory religious organization – no one can ever be coerced to join a discriminatory religious organization, and every member must be genuinely free to leave those ranks as they will. I will state it even more clearly: Permitting religious organizations to engage in discrimination is morally wrong if membership in religious organizations is not genuinely, fully voluntary. I deliberately chose not to emphasize or dwell on the matter of coercing adults to stay within the ranks of religious organizations because it is genuinely trickier, for many reasons – but how free one really is to leave the ranks doesn’t matter one bit if entering those ranks in the first place is not voluntary, and for the most part it is not.
Religious organizations and institutions do in fact discriminate, and they do in fact involuntarily induct many members into their ranks who cannot conceivably give informed consent – not just many, but the overwhelming majority. These facts create a fundamental conflict between the free exercise of religion and other fundamental rights – including the basic rights of self-determination and equal treatment, which are de facto denied to those unfortunate enough to be born to parents who raise them within the confines of discriminatory religious organizations. Since the basic rights of self-determination and equal treatment are the ultimate rationale for guaranteeing every citizen’s freedom of religion in the first place, this conflict is particularly acute.
I am not denying the right of parents to raise their children as they see fit (within reasonable limits), nor am I denying that religious organizations and institutions have the right to conduct their own religious business as they see fit (within reasonable limits), and that the latter right can reasonably be extended even to practices that discriminate on the basis of religion, gender, behavior, etc. What I am asserting is that these rights in combination generate a genuine logical and moral conflict with basic rights to self-determination: The right of religious organizations to engage in discriminatory practices can only avoid conflict with basic rights to equal treatment and self-determination if and when membership in religious organizations is genuinely voluntary – i.e. you aren’t being discriminated against if you entered the discriminatory group of your own free will and can leave at any time – and parents’ rights to impose religion on their children means that an overwhelming majority of members in religious organizations do not become members voluntarily by any reasonable definition.
Of the fundamental rights at stake, I think equality should trump the special protections offered to religion based on the principle of religious liberty: Religious beliefs include bigoted beliefs; I am loathe to extend special protection to the institutionalized practice and enforcement of bigotry simply because it falls under the heading of religion. The presumption that protecting religous freedom always and automatically does require the state to grant unfettered free reign to religiously-grounded sexism (and heterosexism, and so on) simply because it’s religious is exactly the presumption that Ophelia rightly calls into question in her post.
But how best to deal with this in practice is not at all clear. One thing that might help the situation comes from the other line of argument I made: Free democratic states need to fully disentangle themselves from religions, making them the truly private membership organizations they should be.
A good start would be doing more to keep indoctrination out of public schools, and in its place to ensure that children in public education are exposed to neutral, historical and sociological religious education that paints a realistic, non-judgmental picture of religious diversity. That would greatly reduce the coercive character of parental indoctrination: Even if children are taught “the One True Way” at home and church, they will be in a better position to make their own decisions as adults if they have at least been positively exposed to the idea that there are lots of other ways.
Also, state intervention in religion need not be overt or directly coercive. Perhaps the stance of a well-structured, genuinely free democracy ought to be something like the following: “Of course religious organizations have every right to set codes of conduct for their members, determine who they hire and promote to leadership positions, and so on. But we are only willing to grant tax exempt status to non-profit organizations – religious or otherwise – which are willing to make such decisions within the bounds of secular equal rights legislation that apply equally to all citizens and citizen organizations. If the Catholic Church wishes to be a ‘boys only’ club, then they can pay taxes like any other private club or association.”
The approach outlined above seems very defensible to me. There may be reasons to grant religious organizations some special protections and presumptive legal latitude simply because they are religious, in defense of freedom of religion for all citizens: But insofar as freedom of religion entails freedom from religion for those who abjure such affiliations, there should be a principled assumption *against* extending protection or latitude to such a degree that religious organizations and institutions are afforded positive benefits not available to similarly constituted but non-religious organizations and institutions. If a private membership club is not permitted to discriminate, a religious organization should not be: Or, if the state does allow religious organizations to discriminate (on the basis of sex, race, or some other protected category aside from religion itself) in order to maximize freedom of religion, at the very least the state has a legitimate compelling interest (upholding equal rights for all citizens) in and an objective justification for treating a religious organization that discriminates differently from one that does not discriminate. In the U.S., churches that engage in overtly partisan politics theoretically risk losing their tax-exempt status – although in practice this is true more in the breach than the observance. Why not impose the same sort of limitation on churches that engage in hiring discrimination?