Definition
Excommunication is a formal religious penalty that excludes a person from participation in the sacraments and communal life of a church. In medieval Christianity it was the most severe disciplinary measure short of permanent condemnation.
It was intended both as a punishment and as a corrective — a public exclusion meant to pressure the offender to repent and return to the community.
Why it matters
How it works
Excommunication is pronounced by a recognized church authority against an individual judged guilty of grave offense, heresy, or defiance. The excommunicated person is barred from the sacraments and, in stricter forms, shunned by the wider community. Because medieval life was deeply religious, this exclusion carried enormous social and political weight: even kings could be pressured by the threat of losing the obedience of their subjects. When churches excommunicated each other's leaders, the act symbolized — and hardened — a permanent division.