Why are Jewish males circumcised?
According to the Hebrew Bible (Genesis 17:1-14) circumcision was instituted as a sign of the covenant between God and Abraham, to be carried out on the body of all future male Israelite children:
Abram was 99 years old. God appeared to him and said, ‘I am God Almighty. Walk before Me and be perfect. I will make a covenant between Me and you, and I will increase your numbers very much.’ Abram fell on his face.
God spoke to him [again], saying, ‘As far as I am concerned, here is my covenant with you: You shall be the father of a horde of nations. No longer shall you be called Abram. Your name shall become Abraham, for I have set you up as the father of a horde of nations. I will increase your numbers very, very much, and I will make you into nations — kings will be your descendants. I will sustain my covenant between Me and between you and your descendants after you throughout their generations, an eternal covenant; I will be a God to you and to your offspring after you. To you and your offspring I will give the land where you are now living as a foreigner. The whole land of Canaan shall be [your] eternal heritage, and I will be a God to [your descendants].’ God [then] said to Abraham, ‘As far as you are concerned, you must keep my covenant — you and your offspring throughout their generations.
This is my covenant between Me, and between you and your offspring that you must keep: You must circumcise every male. You shall be circumcised through the flesh of your foreskin. This shall be the mark of the covenant between Me and you. ‘Throughout all generations, every male shall be circumcised when he is eight days old.
[This shall include] those born in your house, as well as [slaves] bought with cash from an outsider, who is not your descendant. [All slaves,] both houseborn and purchased with your money must be circumcised. This shall be my covenant in your flesh, an eternal covenant. The uncircumcised male whose foreskin has not been circumcised, shall have his soul cut off from his people; he has broken my covenant. (Genesis 17:1-14)
And in Leviticus 12:3: On the eighth day, [the child’s] foreskin shall be circumcised.
The penalty of non-observance is karet or expulsion from the community, a serious punishment the Bible has in store for all kinds of transgressions. Circumcision is still widely practiced and a prerequisite for male conversion in most Jewish communities. If a convert was circumcised at birth, a symbolic drop of blood will be drawn instead.
Are Jews circumcised at their Bar Mitzvah?
No. Traditionally, male Jews are circumcised on the eighth day of their life in a ceremony called brit milah (Heb. covenant of circumcision) or, in Yiddish, bris. A Bar (or, for girls: Bat) Mitzvah is, like a brit milah, a rite of passage and marks the age of ritual maturity. Today, this is usually 12 for girls and 13 for boys.