Actually, the Greek tells us that John sees 2 distinct groups of souls. You don't get that from reading the NIV and some of the other translations. You ~do~ read of 2 distinct groups of 'souls' from the KJV and NASB if you look closely:
Actually one of the Modern language "teaching "bibles boldly changed the words in one of the verses
Rev 20:4 (KJV) and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands
This does indeed indicate two seperate groups .Those that were beheaded for Christ...and those and those that had not worshipped the beast etc
It is not a legitimate conclusion that they MUST BE 2 separate groups.
A literal rendering would be: "And I saw thrones, and they sat on them, and judgment was given to them, and the souls of "the having been beheaded ones" because of the witness of Jesus and because of the word of God, and who not worshipped the beast nor the image of it and not received the mark on the forehead and on the hand of them; and they lived and reigned with the Christ a thousand years."
The word "hoitines" appears only once and that in conjunction with the clause about the mark and image. The first "who" is understood and is literally, "the having been beheaded ones." It strengthens the rendering of the versions that identify the two groups.
Had they wanted to clearly identify two groups they would have said "and ALSO the ones who."
As it is, the king james actually preserves the fact that there is no "who" in the first clause but there is one (which) in the 2nd clause.
To conclude two groups is to make an assumption.