Dogma (and doctrine, and discipline)

Three words that are often blurred. A dogma is a truth contained in divine Revelation that the Magisterium has proposed in a form obliging the faithful to an irrevocable adherence of faith — the Trinity, the Real Presence, the Assumption. Doctrine is the broader body of the Church's teaching, proposed with different degrees of authority; some doctrine is not, or has not yet been, defined as dogma. Discipline is the Church's practice and law — clerical celibacy in the Latin rite, the rules of fasting, the language of the Mass — which is binding but can be changed by the Church. Dogmas cannot be reversed, though understanding of them deepens.