The well-nigh universal ancient rite of circumcision was an outgrowth of the cult of partial sacrifice; it was purely sacrificial, no thought of hygiene being attached thereto. Later on became a hygienic procedure.  Circumcision was first practiced as a rite of initiation into one of these secret fraternities. 
In many ways and by devious methods the olden shamans established their reputations as voices of God and custodians of providence. They sprinkled the newborn with water and conferred names upon them; they circumcised the males. 
Most of the Salem believers had practiced circumcision, though it had never been made obligatory by Melchizedek.  Abraham, who was against the rite of circumcision, decided to solemnize the ratification of the Salem covenant accepting the rite.