Possible Meanings...
While I think that there are some very religious phrases and undertones to this song, I don't think they are meant religiously at all. Given the broader scope of the song and the fact that there are several phrases that just don't fit in with the religious interpretations, I think that it is more likely a morality tale about power.
It's about absolute power corrupting absolutely. Taking power violently and by force ends with it being taken from you violently and by force. Abuse of power and desire for more end in revolution and violence. Childoftheunderworld I think said it beautifully. There are elements in here that refer to a host of historical figures that held great power and sway and all of them were swept aside in their turn.
It is interested when taken in light of world events at this time. Gordon Brown coming replacing Tony Blair as Prime Minister of England. The elections here in the United States where Bush will be replaced by someone and the general unhappiness of the public at how he ran things. Political turmoils surrounding the removal of Saddam Hussein in Iraq. There are many places right now where the "old king is dead" and "long live the [new] king" is being played out.
Throughout it there is the feeling of the fickleness of the masses and how quickly they can turn on you. The care that is needed as a ruler, especially if you got your power through violent means.
There also seems to be the idea of sorrow at ones past actions and forgiveness. The 2 final repetitions of the chorus are identical except that in the first one he knows that St. Peter WON'T call his name. Then in the 2nd repetition he says that St. Peter WILL call his name. It seems that this person has come to understand that the things they have done were wrong in some way and they feel sorry for that. This could go back to Napoleon and several kings mentioned who were exiled or imprisoned after their defeat and had plenty of time to think about things. This person became penitant. It's almost as if they are approaching their death and they are realizing that their life may not have been this great thing and they are asking forgiveness for it. Could this be a final prayer, recounting their life and trying to change their heart?
The music is incredible and no matter the true meaning of the lyrics, this is indeed a very powerful song.