What does the chaining and locking of Satan in the bottomless pit for the millennial reign accomplish? In my study of the Revelation of Jesus Christ, I am puzzled by the chaining, and the locking of Satan in the Pit for the millennial reign of Christ.
This question: According to premillenial view, What is the point of the Millenium reign? is similar and has an answer that gives two reasons for  the millennial reign, but they do not seem to answer my question.
Here are some considerations that I have mulled over:


Satan is chained and locked in the pit, so that he can no longer tempt mankind.

Since Satan was defeated at the cross, then why is he loosed to participate in the battle of Armageddon?

Is the battle of Armageddon the final battle of the war begun in Heaven, and if so why then did God, give the one thousand year interlude in that battle?

Is the Battle at Armageddon to show Satan that even though he enlisted such a large number of mankind in his army that that was not sufficient to overcome the army of God?

Assuming that number 4 is true, then why does the judgment immediately follow Armageddon?

And finally, will Satan and all unbelievers have to bear the knowledge that their rebellion was such folly for the Eternity in the lake of fire?



Number 6 is as close as I have come to understanding this passage in the Revelation, but it still does not answer my initial question, of the purpose of the millennial reign, and why Satan is bound and locked in the bottomless pit.
From what I know of the Catholic faith they believe that the dead are put into a place known as Purgatory to await the final judgment, which gives a second chance to get into Heaven, but we protestants do not adhere to such a belief. As far as purgatory goes it would give a chance for those in purgatory to get into heaven while Satan was bound which seems a bit of a stretch to me, but as for Protestants it seems to serve no purpose for those who are already dead since their fate is sealed as far as I understand.
I can see a possible reason for Catholics but not for Protestants. Any ideas from any denomination are welcome.
Perhaps the simplest--yet most profound--reason for Satan's being chained for a thousand years is because God desires to prove to humanity once and for all that even with Satan out of the way, human beings will still reject the Lordship of Jesus Christ, thinking they are better off being masters of their own fate instead of subjects of the King of kings and Lord of lords (Revelation 17:14; 19:16).  

In other words, at the end of the thousand years, no one can any longer legitimately blame only Satan for something that is deep within the heart of all of us; namely, our sin nature. 

To be sure, Jesus entered time and space as the God-Man to destroy through his death and resurrection the works of the devil (1 John 3:8), but he did not enter time and space to destroy the sin nature of the creatures he created in His image. That is something each true believer needs to do of his or her volition as they put to death the works of their sinful nature (see, for example, Romans 8:13 and Colossians 3:5). 

What the 10 servants of the nobleman in Jesus' parable said of their master in Luke 19 will also be on the lips of those who refuse to bow the knee to the reign and rule of Jesus on earth during the Millennium:


  "'We will not have this man to reign over us'" (vv.19 and 27).


When Satan is finally loosed from his captivity, he will have little trouble, then, in rallying troops around him in his ultimately futile attempt to depose by force the King of kings and the Lord of lords, Jesus Christ. King Jesus, in turn, will have no difficulty in defeating the prince of darkness and the father of lies, as well as all those who align themselves with him and with the beast and the false prophet. After their defeat, the unholy trinity will be cast into the lake of fire forever (see Revelation 19:20; 20:10; 20:14-15). 

Only then will 


  "'The kingdoms of this world . . . become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever' (Revelation 11:15 KJV).