In Christian tradition, Christ says to St. Peter "I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven." He therefore became regarded as the gate-keeper of heaven. The Papacy, which traced its origins from St. Peter used two keys representing the keys of heaven and earth, in its arms, signifying that the Catholic Church was the medium through which a Christian could enter heaven. Cardinals of the Catholic Church also used St. Peter's keys in their arms. Keys are also widely used in Protestant ecclesiastical heraldry.
