IMHO, there is a much larger percentage of the American demographic influenced by relative morality and comparative religious perspectives than Christian zealots seeking vigilante-ism.
Lots of angry closet LGBT, blacks, Latinos, even Zen-Buddhists out there who would just as soon exact vigilante justice at the ballot box as they would execute known murdering street criminals.
The Dems are the party of the 7 deadly sins.
They thrive by stoking covetousness, anger, etc.