dogma

1590–1600; < Latin < Greek, equivalent to dok(eîn) to seem, think, seem good + -ma noun suffix

At the turn of the 17th century, dogma entered English from the Latin term meaning “philosophical tenet.” The Greek word from which it is borrowed means “that which one thinks is true,” and comes ultimately from the Greek dokeîn, which means “to seem good” or “think.”
The origin of the word dogma acts as a reminder to English speakers that now established principles and doctrines were once simply thoughts and opinions of ordinary people that gained popularity and eventually found their way into the universal consciousness of society. Twentieth-century American academic and aphorist Mason Cooley concisely observed that “Under attack, sentiments harden into dogma,” suggesting that dogma is spawned as a defensive act. This idea implies that for every dogma that exists, there is a counter dogma. With so many “truths” out there, there is sure to be a dogma to conveniently fit every set of beliefs.

— Dogma: A film written and directed by Kevin Smith, released in 1999.
—Dogma 95: A movement in cinema started by Danish director Lars von Trier in 1995, which established filmmaking constraints such as no use of special effects.