"But amid the soul-searching, it is unlikely that Nicholson, himself the object of an intraparty challenge this winter, can keep in check the passions and egos of politicians, some of whom see themselves on a mission from God to save America from itself."
—Scott Shepard, "GOP fearful in fighting will cost elections," Austin American-Statesman
The popularity of this phrase is almost certainly due to its frequent use in the popular movie
The Blues Brothers (1980):
Jake Blues (John Belushi): "First you trade the Cadillac
for a microphone. Then you lie to me about the band.
Now you're gonna put me right back in the joint!"
Elwood Blues (Dan Aykroyd): "They're not gonna catch us.
We're on a mission from God."
