If hades and hell are the same place, how can hell be cast into itself?
Hell in the old testament (H7585) is transliterated Sheowl and it means the grave. Hell is eternal but the grave is thought of as the earth. The earth's crust is probably 2 to 20 miles deep and we know with volcanoes what is underneath. The first earth will be passed away so there will be need of a new hell. Whether you interpret it to be a new hell or Gehenna, the problem is that the term "passed away" (g3928 παρέρχομαι parerchomai) indicates "to perish":
Revelation 21:1 ¶ And I saw a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea.
Hell is eternal as we will see but Jesus said "I am alive forevermore" and they are the same words translated "forever and ever". If some versions translate God as everlasting then you have no choice but to translate hell as being everlasting because the different translations use the same words for both hell and God. Since the old heavens and the earth will pass away, the old location of hell will be passed away or thrown into the new location which is the lake of fire.
Jesus said,"I am the first and the last, and the living One; and I was dead, and behold, I am alive forevermore [eis tous aionas ton aionon] (Rev. 1:17-18, NASB).
Revelation 20:10: "And the devil who deceived them was thrown into the lake of fire and brimstone, where the beast and the false prophet are also; and they will be tormented day and night forever and ever [eis tous aionas ton aionon]."
Not one of these translations translates "aionion" as anything other than "eternal" or similar.http://bible.cc/matthew/25-41.htm
Revelation 20:13 And the sea gave up the dead which were in it; and death and hell delivered up the dead which were in them: and they were judged every man according to their works.
Revelation 20:14 And death and hell were cast into the lake of fire. This is the second death.
Death and hell delivered up the dead. And death and hell were cast into the lake of fire indicating that it isn't the same location.
Revelation 20:15 And whosoever was not found written in the book of life was cast into the lake of fire.
The people in hell were then cast into the lake of fire indicating a different position.
"Verse 5: 'But the rest of the dead lived not again until the thousand years were finished. This is the first resurrection.'
"The 'resurrection of the just' is mentioned in Luke 14:13-14, and the 'resurrection of life' is definitely distinguished from the 'resurrection unto damnation' in John 5:29. Here in Revelation 20:5 we learn for the first time the interval that separates the two resurrections: One thousand years. When Jesus comes in the Rapture, only the righteous will be raised (I Thess. 4:13:18).
"When He comes in the end of the ages, only the wicked will be raised and will appear before the great White Throne to be judged. The doctrine of a general resurrection- a time when the good and bad, just and unjust are raised-is certainly disproved by this text. In John 5:28-29 we read, 'Marvel not at this: for the hour is coming, in the which all that are in the graves shall hear His voice, and shall come forth; they that have done good, unto the resurection of life; and they that have done evil, unto the resurrection of damnation."
-p.487, The Revelation, Verse by Verse Study, The Gospel Hour, Inc., Dr. Oliver B. Green.
"The throne set up in Matthew 25:31 is not the great White Throne of Revelation 20:11. The former was set up before the Millennium, and the parties judged there will be living persons on earth-the sheep and the goat nations. The great White Throne judgment is set up to reward all the wicked dead according to their wickedness. The judgment in Matthew 25:31 has to do with nations; the great White Throne judgment has to do with individuals."
John 5:24 ¶ Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation (judgment) ; but is passed from death unto life.
If it says we shall not come into judgment then where is the judgment to remove us as adopted sons and daughters? If Jesus says we have not come into condemnation (judgment) then why would we be present in the white throne judgment? The verse says 'hath' eternal life. It doesn't say 'might have' or 'could have' and I'll give you an example:
If we can't get into heaven then how would Paul get into heaven because he murdered Christians and the law said that murderers should be put to death (Numbers 35) and that 1 John 3:15 says that no murderer has eternal life abiding in him and Moses who killed an Egyptian (Exodus 2:4) was at the mount of transfiguration (Mark 9:4)? The only way for Moses to be there is for someone to pay our ransom and take our place.