St. Augustine almost certainly liked a good poop joke, actually
In this shocking panel, Marvin has taken two thousand years of theology and turned it on its head. In a direct riposte to Calvin, who started from the premise of an omniscient, omnipotent God and declared that our ends were predestined before we were created, leaving any seeming room to maneuver an illusion, Marvin instead preaches the existence of a smug, all-knowing narc, who gave us the power to shape our own destiny just to revel in the certain knowledge that we’ll screw it up and condemn ourselves to damnation. Whether or not you agree with him, you have to admit it’s a welcome change of pace from the constant poop jokes.
It strikes me as a pretty short trip from “I’ve no way to follow them” to “So why should I even try?” and from there to “I wonder what’s on TV!”