CCC 392 Scripture speaks of a sin of these angels.1 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.”2 The devil “has sinned from the beginning”; he is “a liar and the father of lies”.3

1 Cf. 2 Pet 2:4.
2 Gen 3:5.
3 1 Jn 3:8; Jn 8:44.