Trinity
The doctrine that the one Godhead or first principle subsists as three co-equal aspects or persons rather than a bare unity — the Christian Father/Son/Holy Ghost invoked in the recurring liturgical formula 'In the Name of the Father, and of the Son, and of the Holy Ghost,' but structurally the same pattern as the Egyptian Amen/Ptah/Osiris, the Hindu Brahma/Vishnu/Siva, and the Kabbalistic Chochmah/Binah/Kether triads that esoteric writers explicitly map onto it as instances of one universal law. Distinct from unity_of_being (the general claim that all existence is one substance, agnostic about internal plurality) and divine_simplicity (God as having no parts or divisions at all) in asserting a definite three-aspected differentiation within a single divine essence.