The Bible says it was demanded by God as a sign of his pact with Abraham. God may move in a mysterious way but this really is extraordinary. Why give it to us then tell us to cut it off? In fact the tradition went back long before Abraham and was widely practised in the ancient world, except in Babylonia and Assyria.
Herodotus said it began with the Egyptians, though he did not know why, and archaeology proves that it was practised there five thousand years ago. In many places it seems to have been done at puberty for both boys and girls. In an age without painkillers or antibiotics this must have resulted in terrible infections and many fatalities, as it still does in parts of Africa.
Greeks and Romans never seem to have done it and thought it was crude and uncivilised. Under their influence the practice gradually disappeared. Some Jews even tried to reverse the effect, though how is not said! Satirists like Juvenal and Martial were particularly caustic, saying it was an example of Jewish barbarity and superstition. When Hadrian tried to ban it, however, he prompted the Jewish revolt led by Bar Kochba. Clearly new Christians, most of whom would have been adult gentiles, were having none of it and it had ended within their community even in biblical times.
None of this however explains where it came from, or why.
The Rev NEIL DAWSON