Islam has no ordination, no sacraments, and no priesthood: authority is scholarly, earned through years of study with recognized teachers, and it is plural by design. An imam is whoever leads a given prayer; a mufti issues non-binding opinions; a qadi judges in a court. Four Sunni legal schools have coexisted as equally valid for a millennium, which is a genuine structural pluralism. Shia Islam is more centralized through the marja'iyya, where believers formally follow a living scholar's rulings.