If there was a tribe who considered cannibalism and ritual sacrifice an essential part of their religion, would you also defend that practice? There is a line which cannot be crossed, we're just debating where it should be drawn.
I don't think religion has any bearing on whether something is acceptable or not. The Hopi may beat their children for religious reasons, but plenty of parents beat their children for non-religious reasons. What matters in the question of whether this should be allowed is not the reason why they do it, but the consequences of doing it. Laws regulate actions based on their consequences, not based on their motive.
Religion is an integral part of culture though, so an attack on religious practice is an attack on cultural integrity. This is why I support the Supreme Court's decision in Yoder v. Wisconsin, holding that the Amish in the US have a right to educate their children to Amish religious standards instead of the standards the state sets, even if, as Justice Douglas noted in his concurring opinion, this means someone raised as an Amish will never be able to be an astronaught.
The fundamental question is how much deference we give to culture generally and who is making these decisions. Do we want white folks telling Hopi they can't have what remains of their culture anymore? Do we want folks from China and India telling white Americans what should constitute free speech?
My view is that if we don't allow for local culture and decisions about such things to be made at the local and cultural level then we lose our basic humanity. For cannibalism or ritual sacrifice, if it is internal to a population group, I think that this is for that group to work out. If it is between groups, well then that's cause for war.....
A lot of things in culture are really structurally variable. For example is it a human right to be able to choose not to ever have children? Does this mean that cultures that expect retirees to be cared for by their children are violating human rights and every culture must have something like social security? Now, if you agree that's a cultural issue, then something like same-sex marriage also must be a cultural issue too.
(Religion, in my view, isn't about God. Religion is about community.)
I don't think religion has any bearing on whether something is acceptable or not. The Hopi may beat their children for religious reasons, but plenty of parents beat their children for non-religious reasons. What matters in the question of whether this should be allowed is not the reason why they do it, but the consequences of doing it. Laws regulate actions based on their consequences, not based on their motive.