One of the most often misspelled religion-oriented words in English is "sacrilegious."

[MineralMan]

People most often misspell it as "sacreligious," thinking it is based on the word religious. They rarely spell it correctly, and are often surprised when their spell-checker flags their spelling as incorrect.

That's because they don't understand the origins or etymology of the word, which really means "stealing sacred things," "misusing sacred things," or "showing disrespect for sacred things." Sacrilegious comes from two Latin words, sacer and lego, which translate to the English words, sacred and steal.

So, when I say something you think is disrespectful to religion, or make a joke about religion, please spell your insult correctly. I am being sacrilegious, not sacreligious. There is no "religious" in sacrilegious.