Why are most men in America circumcised? It turns out that it has a little bit to do with religion and a lot to do with a fellow named Kellogg.
Apart from those in the Jewish or Muslim faith and a few African tribes most men in the world are not circumcised. America is one of the only cultures that practices circumcision.
A lot of it has to do with tradition, but that tradition started around 1900s with a bunch of puritanical doctors who pushed it as a way to stop boys from committing their favorite sin.