There are few aspects of Jewish life that have been debated as heatedly as circumcision. It's physical. It's permanent. It effects an area of the body that most people today won't even discuss in proper company.
Most recently, the citizens of San Francisco, Calif., faced a potential vote on whether to make it a misdemeanor to circumcise any male under the age of 18. The referendum, which was to be held in November, will not take place because California Governor Jerry Brown has passed a law banning any bans on circumcision.
While many Americans were surprised by the proposal, and great debates raged on the Internet, this would certainly not have been the first time that circumcision has been outlawed. The most famous prohibition of circumcision occurred when the Syrian-Greeks sought to force Hellenization on the Judeans (in the era of the Maccabees and Hanukkah). Performing a circumcision on one's child became a capital crime. The Syrian-Greeks found circumcision particularly offensive because of their own culture's devotion to the beauty and perfection of the human body. The ancient Greeks are renowned for their sculptures and naked athletics. From the perspective of Hellenistic culture, the male body represented perfection. It was therefore unconscionable that the Jews should alter it, or maim it, especially by Divine decree.
According to Rabbi Shimon ben Eleazar, as quoted in the Talmud: "Every precept for which Israel submitted [themselves] to death at the time of the royal decree [of the Syrian-Greeks], e.g. idolatry and circumcision, is still held firmly in their [the Jews'] minds" (Shabbat 130a).
Brit Milah, as circumcision is called in Hebrew, is a mitzvah that has withstood the test of time. Even Jews with only a tentative connection to Judaism still have their sons circumcised. Perhaps it is because this is a mitzvah that is done joyously (accompanied as it is with a festive meal) as it not only affirms the parents' connection with Judaism, but the child's link as well. According to Rabbi Shimon ben Gamliel, the joy with which the Jewish people accepted this mitzvah is the reason that it is still observed.
Brit Milah is so important a mitzvah that the Talmud states: "Great is circumcision, for it counterbalances all the [other] laws of the Torah" (Nedarim 32a). In fact, circumcision is so important to the Jewish people that it is one of only two commandments for which the punishment of kareit (being "cut-off") is applied if they are not fulfilled. (The other is the offering of the Paschal lamb in Temple times and when one was not in a category allowing for exemption).
Kareit, often defined as excision, is extremely hard to comprehend. In fact, the sages of the Talmud even debate what this punishment is. Many sages and rabbinic leaders have also noted that kareit may have a different effect on people today than it did in the days of the Holy Temple. It is believed that, in times when our connection to the spiritual realm was more tangible, kareit was actual death. (Not instant death, but rather death at a young age -- under 60 -- accompanied by a lack of further offspring.) But kareit is also understood as a spiritual excommunication, in which one's soul is cut off from God.
Why is circumcision so important to God? The plain fact of the matter is that we do not know. While numerous explanations for the ritual have been suggested by different sages throughout the generations, circumcision is a chok, a law that is performed as God's decree, and according to traditional Judaism, no further explanation is needed.
No arguments can be addressed to those who do not recognize the concept of sanctification or the importance of heritage. Claims that an act of tradition are barbaric need no reply. For those who wonder about the safety of circumcision, however, it must be stated that fulfilling a mitzvah at the risk of someone's life (even one's own) is a severe transgression of Jewish law. There are only three exceptions to this rule: one must give up one's own life rather than take the life of another, commit an act of sexual immorality or worship idols. Although it is commanded that the brit milah be performed on the eighth day, a mohel (one trained to perform brit milah) will not perform the ritual on any child who is not in perfect health.