Venerable Order of Saint John
The order's approximately 25,000 confrères, supported by 4,000 employees and 250,000 volunteers, are mainly Anglicans, though those of other Christian denominations or other religions are accepted into the order, and honorary membership is presented to distinguished adherents of other religions. Membership in the order is by invitation only, except via appointment to certain government or ecclesiastical offices in some realms.  People may not petition for admission. It is perhaps best known through its service organizations, St. John Ambulance and St John Eye Hospital Group, the memberships and work of which are not limited to any denomination or religion.