This lyric could easily be about Aladdin mocking Prince Achmed only to basically try and be Prince Achmed one he becomes Prince Ali Ababwa.
They say that what you mock
U2 Peace on earth
Will surely overtake you
And you become a monster
So the monster will not break you
And, if I were witty – I would have just quoted Bono. Instead, I went for Nietzsch and pretty royally biffed it. (pun intended)
From the Genius.com annotations
This is an oft-used quote in Bono’s lyrics, by philosopher Friedrich 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.”
JWG