Back when the Jews were invented, Yahweh decreed that all male babies were to have their foreskins removed. It was merely one in a long list of detailed rules surrounding your entire life, demanded by the god of the Old Testament. Mutilate your child's penis, or risk a smoting.
Bafflingly, people are still doing this today. Despite many, many Old Testament provisions that even the most fundie theists completely ignore, virtually all of them, and a good number of non-Christians as well, still circumcise their children.
(Am I the only the one who sees the inherent contradiction between "God made our bodies perfectly as they are," and "There is a part of the human body that offends God and must be removed as soon as possible?")
But today, you can't offer as a reason for performing an invasive surgical procedure on an infant something so banal as "God told me to do it," and expect to be taken seriously. So now they offer pathetic "arguments" for routine infant mutilation.
Such as: Circumcised men have better sex. (No, they don't). Circumcised men have less chance for acquiring AIDS and other STDs. (Yes they do, but only very slightly less chance; see above link.) There's also the argument that ... Oh wait, those are the only two arguments pro-circumcisors ever give.
Okay, you might be saying. Circumcision offers a slightly less chance of STDs. Isn't that reason enough to routinely circumcise? No, of course it's not. Since when is it acceptable to perform an invasive sugical procedure on an infant because of slightly less chance for disease later on? I'm sure that routinely removing the appendix from newborns would decrease their chance of appendicitis later on. But no one would seriously advocate that. If your son grows up and decides he wants to remove his foreskin, by all means he should have the right to do that. But forcing it on infants who cannot understand what is being done to them is unconscionable.
Now, some hardcore anti-circumcisors say that parents shouldn't even be allowed to circumcise their children. I disagree. I think parents should still have broad rights to decide what medical procedures should be performed on their children. But they should choose not to perform this one.