He was talking about the sermon that Pastor Liz was giving to her congregation, and it had to do with a poor man begging for some food from a rich man who dismissively throws him only crumbs. Near the end of the sermon, Pastor Liz gets to the part where both men have died, and the poor man has made it up to heaven, while the rich man to his surprise finds himself down in Hell and suffering, deeply thirsty from the heat.
At this point, then, let's pick up Keillor as he finishes quoting what Pastor Liz was saying in her sermon --
"'And the rich man begged, begged Abraham for a drop of water to put on his tongue. And Abraham said, 'In your lifetime, did you share with your begger more than just the crumbs off your plate? No, you did not.'
"It's a harsh, hard lesson with a clear moral," Keillor then said as his own voice, wistfully. But then he paused a long moment, and his tone changed to a bit more quizzical.
"And yet --" another pause " -- Congress did vote to take billions away from the food stamp program..."
The audience burst into loud and long, sustained laughter. With almost a shrug in his voice, he continued:
"Nonetheless, people go their own way..."
And as his voice faded off, the auditorium broke into applause and more laughter.