The Noose is about a man who committed an act which caused several people to die (whether it was murder or not was unspecified, so it is possible that it could have been manslaughter, or just a freak accident).
The song uses the Metaphor of a Halo to describe the mans new found peace in his consciousness, but the Metaphor Doubles as the Halo falls around the mans neck, and becomes his noose.
When Maynard says "with Heaven's help" he is alluding that the man who killed the people is finding rest by using religion to atone for his sins.
It is likely that he is referring to Christianity, where if the person believes that Jesus Christ died for their sins, they are absolved of any sins.
The Halo in this case is representative of the man's New Found forgiveness, and is using the idea that a Halo is "holy" or "righteous".
Maynard then says "And not to pull your halo down". He says this in a way that is similar to "Not to burst your bubble but...".
With this line, and the few that follow, he is saying "Not to Burst your Bubble but, how are you planning on fixing what you have done. Are you going to bring all the people that you killed back to life?".
That is the meaning of the entire song. Everything else in the song is a variation of these two metaphors (the halo and the noose).
I think this is what A Perfect Circle does best. They take just 1 idea, and make an incredibly powerful song in order to get that idea across as well as possible.
Take a look at the rest of the lyrics if you feel you don't quite get the song yet.
My name is Andrew Muller. I love creative art, music, television shows, movies, video games, and a good story.
If you had to find me somewhere, you would probably find me down at O'neils home cooking eating an organic sweet-potato bun breakfast sandwich with ham.
Among my friends, it's a "Muller Classic Move" to eat Mcdonald's at 2am because it's cheap and open 24/7. The joke here is that I'm an idiot.
I play drums, guitar, piano, and I write & perform music for My Goal Is Telepathy. Take a listen to the latest sound here.