1) Protestantism 
• (n.) The doctrine of the Trinity; the doctrine that there are three distinct persons in the Godhead.
Belief in the Christian Trinity. ...
[n] - Christian doctrine stressing belief in the Trinity
noun Christian doctrine stressing belief in the Trinity
a) Referring to a Roman Catholic order founded in 1198 to redeem Christian captives from Mohammedans. b) The usual meaning of the term the doctrine of the Trinitarians who hold that the nature of God is one in substance and three in embodiment (Latin: persona). Upon the basis of Platonic realism (q.v.) which makes the universal fundamental and the....
Belief in the Christian Trinity