He who sins is of the devil, for the devil has been sinning from the beginning. To this end the Son of God was revealed, that he might destroy the works of the devil.
The Scriptures do not give a categorical answer to the question of Satan's origin; but  Ezekiel 28:12-19 has the nearest approach to an answer.  If, as usually thought, "King of Tyre" in that passage refers to Satan, who had been "in Eden," who was lifted up because of his beauty, who "was created," who was perfect in his ways "till iniquity was found" in him, whose heart "was lifted up" because of his beauty, who was "corrupted" because of his wisdom, etc., then the origin of Satan is revealed in that remarkable passage.