Parents make decisions of debatable cost:benefit for their children all the time. If I want to initiate my kid in the mysteries of the Golden Dawn, that's my choice. If he had the choice he probably wouldn't want to, but as a parent it's my right to choose for my kid what I think is best, and if someone thinks something I choose should be prohibited, the burden of proving it should be on him.
Belief is not equivalent to action. Cults are intangible social organizations, circumcision is a physical body alteration. That's a key difference.
Parents have a lot of power over their children, it's true, but they don't
own them. A child's afforded power and rights ideally grows as they do and eventually ends in adulthood, but at no point does the child have no rights or power. From the moment you are born you are automatically afforded all basic human rights, and one of those is freedom from unnecessary pain or mutilation without the individual's express consent. Note the qualifier "unnecessary", hence why I don't oppose vaccinations like I do circumcision. The former has a very important purpose that protects all of human society from disease, while the latter does nothing of the sort.
I will preemptively address the claim that circumcision does in fact do that by lowering the chance of HIV infection with the following arguments:
-The U.N study that is primarily used as a source for this claim has been repeatedly disputed in accuracy and scientific rigor. Especially concerning are the reports that the U.N. intentionally ended this study early when the results started to not portray circumcision as preventing HIV infection. While said claims alone are not enough to prove the study is actually illegitimate, they are concerning enough in light of the U.N.'s unimpressive track record in not letting politics influence their actions that it would be preferable to rely upon other studies on the same topic.....if any existed, which as I remember, they did not last time we had this discussion.
-Assuming that circumcision does, in fact, lower the rate of HIV infection in men, it is no more a justification than preemptively removing the breasts of infant girls to prevent the possibility of breast cancer later in life.
-Adding to the unnecessary nature of this even if it is true, HIV infection rates have peaked and lowered both in the United States (high circumcision rate) and the European Union (low circumcision rate). This suggests that circumcision as HIV protection does not have any effect on a societal level.
-As most of you probably remember, a HIV vaccine is currently in third-stage human trials in Canada and is showing promising results. Assuming it doesn't fall through we could be immunizing people to HIV entirely by 2015 or so, thus rendering every other HIV protection method moot.