Catechism number 392

Scripture speaks of a sin of these angels.²⁶⁹ This "fall" consists in the free choice of these created spirits, who radically and irrevocably rejected God and his reign. We find a reflection of that rebellion in the tempter's words to our first parents: "You will be like God."²⁷⁰ The devil "has sinned from the beginning"; he is "a liar and the father of lies".²⁷¹