It was widely practiced in the ancient Near East, though not in Mesopotamia from where Abraham and his clan migrated. Many of the building blocks of the Torah are borrowed from surrounding cultures. The most notable example is the system of animal sacrifices as the preferred way to worship God. The synagogue, with verbal prayer based on a sacred book, is the true religious breakthrough of Judaism and not the tabernacle in the wilderness or the temple in Jerusalem. The originality of the Torah often lies in its inspired recycling of older religious materials.
Adroit adaptation invests a common custom with new meaning that is often stunning.
Such is the case, I submit, with the covenant of circumcision instituted in this week's parasha. At the age of 99, Abraham is asked by God to circumcise himself and all the male members of his household. The purpose of a symbol is to convey meaning. Outside of ancient Israel, circumcision is usually a puberty rite, clearly related to fertility. The removal of the foreskin admits the young male into manhood by readying him symbolically for procreation.