Jesus, I ain't trying to be facetious, but
"Vengeance is mine" sayeth the Lord, you said it better than all
Jay paraphrases Romans 12:19, which is actually an admonishment to let God do the killing instead of resorting to violence.
Oddly, Jay interprets it as an endorsement of Earthly revenge, rather than divine revenge, which is why the choice of phrase could be seen as facetious.
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