Who is Satan?

The Catholic Answers

The word Satan in Hebrew means one who is adverse, and it can refer to any adversary. In that sense Christ said on one occasion to Peter, “Go behind me, Satan, thou art a scandal unto me.” Matt XVI., 23. Satan therefore does not always refer to the devil. But since the devil, once Lucifer or the angel of light, is the greatest of all enemies to God and mankind, the word Satan has been applied in a special way to him. Of all adversaries, he is the adversary.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty