Formal and material principles of theology

Formal principle and material principle are two categories in Christian theology to identify and distinguish the authoritative source of theology (formal principle) from the theology itself, especially the central doctrine of that theology (material principle), of a religion, religious movement, tradition, body, denomination, or organization. A formal principle tends to be texts or revered leaders of the religion; a material principle is its central teaching.

Source: Wikipedia — Formal and material principles of theology (CC BY-SA 4.0)