The Lake of Fire is mentioned only in the book of Revelation. Ask any Christian and their imaginations will come alive with ideas about the Lake of Fire. But what exactly is this Lake of Fire or more importantly what is it's purpose? Consider:
20 And the beast was seized, and with him the false prophet who performed the signs in his presence, by which he deceived those who had received the mark of the beast and those who worshiped his image; these two were thrown alive into the lake of fire which burns with brimstone.
Okay, we see here that the Beast and false prophet are cast into this lake of fire. What else do we know:
10 and the Devil, who is leading them astray, was cast into the lake of fire and brimstone, where [are] the beast and the false prophet, and they shall be tormented day and night -- to the ages of the ages.
Here we see that the devil will be thrown into this lake of fire. What else:
8 But for the cowardly and unbelieving and abominable and murderers and immoral persons and sorcerers and idolaters and all liars, their part will be in the lake that burns with fire and brimstone, which is the second death.”
15 And if anyone’s name was not found written in the book of life, he was thrown into the lake of fire.
From these two verses we can see that ANYONE (HUMANS) not found written in the book of life was thrown into the lake of fire. What else:
14 Then death and Hades were thrown into the lake of fire. This is the second death, the lake of fire.
There you have it; ALL the verses that mention the Lake of Fire. I left Revelation 20:14 until last because it gives us a link to understanding what this lake of fire is and its purpose. John saw where DEATH was cast into the lake of fire. This is important to know because another writer talks about death as well. Consider:
1 Corinthians 15:25-26
25 For He must reign until He has put all His enemies under His feet. 26 The last enemy that will be abolished is death.
Paul tells us that Christ must reign until God has put ALL his enemies under his feet. Paul then goes on to say that the LAST enemy will be death. Paul makes sure to say the 'LAST' enemy because there are other enemies that will be abolished. Who are the other enemies? John lists them in Revelation 19:20, 20:10, 21:8 and 21:15 (see above). Altogether the enemies of God are those who REMAIN disobedient in this age. These enemies of God are all to be abolished as Paul says. So how does God abolish death? John tells us how; God abolishes death by casting it into the Lake of Fire. Now here is where the purpose of Lake of Fire is revealed.
John says that Death along with the enemies of God will be cast into the Lake of Fire, Paul says that death and the enemies of God will be abolished. But what does abolish mean?
1 Corinthians 15:25-27
25 For He must reign until He has put all His enemies under His feet. 26 The last enemy that will be abolished is death. 27 For HE has put all things in SUBJECTION under His feet.
Paul tells us that the enemies of God will be abolished BY being SUBJECTED under the feet of Christ. Okay, let's look at this:
John says ALL the enemies of God will be cast into the Lake of Fire.
Paul says ALL the enemies of God will be put in subjection under Christ's feet.
Therefore, we MUST conclude that the 'Lake of Fire' and 'Subjection under the feet of Christ' has to be the SAME thing. So how do we find out what is the purpose of the Lake of Fire? We discover its purpose when we understand the meaning of the word 'SUBJECT'. The word subject in this passage is the Greek word 'hupotasso', and this word means, 'TO BRING UNDER CONTROL AND TO MAKE OBEDIENT'. Now we can see the purpose of the lake of fire:
The Lake of Fire is a process used by God to bring ALL His enemies under control thus MAKING them obedient to Christ.
It is AT this point when ALL the enemies of God, that is, everyone not written into the book of life because of DISOBEDIENCE will be MADE OBEDIENT.
Those chosen by God are made obedient NOW, but later ALL will be made obedient. (See post 'Everyone will be salted by Fire')