Lyric discussion by dikoduck 

geez. no one pays attention to the real history of a song anymore. This movie is NOT an anti-war song, or anything like that. This was a song written FOR A MOVIE, thus, to tie in with the script. In the movie, entitled Pat Garrett and Billy the Kid (i thinkthats the right title), the song is about Pat Garrett, and outlaw who is made into a sheriff and ordered to hunt down his old friend billy the kid. "Mama, take this badge off of me, I can't use it anymore." It's the sheriff's badge, he has no desire to be one when it becomes clear that he must help kill the lifestyle he truly loves. Those are the facts, but in a specific sense I take the knockin' on heaven's door to be about how close Garret is to being an outlaw again, his heaven. In the non-movie related sense of the song, I think it's about a man deciding to be killed rather than fight back, and he's going to die, but he thinks his decision puts him at heaven's door.

@dikoduck I think it is even more simple than that. It is literally a lawman who realizes he is risking his life and he can't do it anymore. Hence the reference to black clouds and things getting too dark. If dying and going to heaven was done through a doorway then knocking on that door would be risking your life.

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