Dictionary:

irreverence

  (ĭ-rĕv'ər-əns)

1. Lack of reverence or due respect.
2. A disrespectful act or remark.

noun

Lack of proper respect: disrespect, lese majesty. See respect/contempt/standing.

Definition: disrespect
Antonyms: regard, respect, reverence

The noun has 2 meanings:

Meaning #1: an irreverent mental attitude
  Antonym: reverence (meaning #2)

Meaning #2: a disrespectful act
  Synonym: violation

Quotes:

"Impiety. Your irreverence toward my deity." - Ambrose Bierce

"Conventionality is not morality. Self-righteousness is not religion. To attack the first is not to assail the last. To pluck the mask from the face of the Pharisee is not to lift an impious hand to the Crown of Thorns." - Charlotte Bronte

"True irreverence is disrespect for another man's god." - Mark Twain

"In America few people will trust you unless you are irreverent." - Norman Mailer