Since weapons of the enemy were considered unholy, the meaning became "anything dedicated to evil" or "a curse". "Anathema" was initially used in its ecclesiastical sense by St. Paul to mean the expulsion of someone from the Christian community. ... "He shrank from the venerable saint as if to avoid an anathema."

Is anathema a curse?

noun A curse or denunciation pronounced with religious solemnity by ecclesiastical authority, involving excommunication.

Is an anathema correct?

When you use "anathema" to denote a curse or denunciation, place an "an" before it ("the witch hurled an anathema at Hansel"). But when you use it to mean something you detest, drop the "an" ("the witch's cannibalism was anathema to Hansel, especially when he spotted her menu"). ... Remember, "anathema" is a powerful word.