Note 4 at Mk. 5:9: Mark and Luke record Jesus asking the demon his name while Matthew does not. In 1 John 4:1-3, we are told to try (test, discern, examine) the spirits to see if they are of God. Discerning of spirits is one of the manifestations of the Spirit mentioned in 1 Corinthians 12:10.

According to Mark and Luke's account of this passage, Jesus' command of "come out of the man" was not met with a quick response as in other cases of deliverance (Mk. 1:25- 26; Lk. 4:33-35; 9:42; 13:11-13). It appears that finding the "spokesman" for the demons (who identified himself as "Legion") was important in this case. Once the "strongman" (Mt. 12:29) of the group was exposed by identifying himself at Jesus' command, the other demons, whose power would be less than their leader, would follow him as he left the man's body.

Whether Jesus actually did not discern the legion of demons, or if He did but chose to use this incident as a means to teach His disciples, the demons still knew Him and His authority and the demoniac was delivered. Jesus gave that same authority to His disciples (Mt. 10:1,8; Lk. 10:1- 20).