I especially like the lines "And you become a monster, so the monster will not break you" - so pertinent to how we handle conflict in the contemporary world as well as across history (burning witches, etc.). It has been documented that the line comes from Nietzsche: “Whoever fights monsters should see to it that in the process he does not become a monster. And if you gaze long enough into an abyss, the abyss will gaze back into you.†I think the rewrite by Bono is more contemporary/human/vulnerable - "Who said that if you go in hard, you won't get hurt" - so I applaud him.
Some interesting commentary on the lyric, collated on wiki:
Irish journalist Niall Stokes calls "Peace on Earth" the band's most "agnostic song yet", saying that it "takes that sense of abandonment" felt in "Wake Up Dead Man" "a stage further". Bill Graham echoes this view asking if this is "'Wake Up Dead Man' part two?". Exclaiming that, "Bono does little to hide the bitterness as he spits out the words "peace on earth".Critics have also compared and contrasted the song with the band's earlier single "Sunday Bloody Sunday". Višnja Cogan writes the "two songs deal with the same subject: the conflict and violence in Northern Ireland, whichever side it comes from. However, 'Sunday Bloody Sunday' deals with an historical event and is approached in a particular way: the ideas of surrender, forgiveness and neutrality are very much present. "Peace on Earth" was written in the aftermath of Omagh and is much more emotional." Ryan Jones of the Bergen Record felt that "Peace on Earth" contained echoes of the band's 1987 song "Mothers of the Disappeared" in its lyrics and the tone of the instrumental prelude.