Reposted, with permission, from Grahams of Montrose.
Satan exists and his aim is to attack Christians. Satan is the chief of demons. He is identified as the serpent of old, Satan (cf. Rev 12:9) who deceived Adam and Eve so that they took and ate from the tree of the knowledge of good and evil (Gen 3). Just as he deceived our first parents, he continues to deceive men today. Jesus told the religious leaders of his day, “You are of your father the devil, and your will is to do your father’s desires. He was a murderer from the beginning, and has nothing to do with the truth, because there is no truth in him. When he lies, he speaks out of his own character, for he is a liar and the father of lies” (John 8:44). Satan is a murderer, a deceiver, and behind false religion.
Demons are fallen angels and share the same purpose as Satan, to attack and control men of the world for evil purposes. That this is true is illustrated by Jesus’ ministry of casting out demons (cf. Matt 8:16). Demons can control people against their desires (Matt 8:28-34) and even cause physical handicaps (Matt 9:32-33). These are only a selection of the many things demons can do in the world.