And Jesus asked him, saying, What is thy name? And he said, Legion: because many devils were entered into him. LUKE 8:30

LUKE 8 is a power chapter for Jesus!  Several of the miracles for which He is most famous are poured into the mold of a single chapter so we get a clear image of the power of the Son of God.  While the chapter begins with teachings, it is loaded with doings.  When Jesus and His disciples go sailing into a storm, the miracle is realized in Christ commanding, and the sea obeying.  Jesus and His disciples encounter a multi-possessed demoniac.  But by the time they leave Him, Jesus commands, and the demons obey in leaving.  Even the former demoniac walks into the pattern after He wanted to join the disciples.  Jesus commands, and the healed man obeys by returning home to testify of all that Christ had done for Him.  A woman full of sickness but more full of faith, just touches Jesus and she is healed!  Afterward, Jesus commands, and the woman who had uncontrollable blood flow obeys and goes home in peace.  Then a dead girl.  So dead that she is confirmed dead by a messenger and is literally being grieved.  Jesus commands "Maid, arise", and the breath of God returns to her and she "arose straightway". 

If you are keeping score at home, so far, fatal storms, demons (plural), chronic illness, and even death, have all taken their seat in the back of the classroom of Christ where He has bound them and put them in their place.  In effect, Jesus commanded, and they all obeyed.  But verse 30 is slipped in like a footnote to help us see something.  The choice and danger of disobedience in contrast to the power of God's commands.  LUKE 8:30 is a rare move - Jesus holds a conversation with the demons.  Already knowing all things, it appears that Jesus conducts this discourse for our sakes.  For the sake of His disciples on scene and us thereafter to understand just how this dude became a demoniac in the first place.  When Jesus asks the demon (singular) his name.  The demon responds with a plural name "Legion: because many devils were entered into him."  Rather than giving a personal name the demon reveals a group name; a gang name.  And more importantly, this was a crew whose numbers increased over time because the Scripture does not say that the demons invaded.  The word used is that they entered.  While this man's soul had become occupied, it was not achieved by assault; but rather, by access.  By saying that they entered, the Scripture is revealing that this state of possession was acquired through contractual agreement, and not conquest.  Each demon got their seat by ticket and not by taking. 

So how did the nameless man get where he was?  If every miracle of God was the result of Christ commanding and someone/something obeying, every advance of Satan (Christ's adversary) was the result of Christ commanding and the man disobeying.  Satan's demons could only advance as the man avoided the will of God.  Every step from God is a step to Satan.  Disobedience to God is simply obedience to self and/or Satan.  The demoniac's condition reveals that there is no Satanic affiliation, occult practice, paraphernalia, or magic required to be controlled by the enemy of our souls.  It's why even today the core principle of modern-day Satanism is "do as thou wilt, shall be the whole of the law."  Disobedience to God is serious because it's still obedience, but not to God.  When we don't open the door of our heart to God, we still have that God-given heart and it still has a door that by design will be open, but not to the one Who created it.  The demoniac's disobedience granted access, but thanks be to God - Jesus still came knocking!  In fact, the Bible says He still knocks at the door of every heart:

Behold, I stand at the door, and knock: if any man hear My voice, and open the door, I will come in to him, and will sup with him, and he with Me. REVELATION 3:20

Let's take our cue!  The LORD is so desperate we get it, He used a fatal storm, a chronic condition, death, and a whole legion of demons as visual aids to get us to look, to "Behold, I stand at the door, and knock..."  He commanded them, and they obeyed.  Will we do the same?