Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

This comic opens with someone asking why the Amish, who are among God's most pious followers, are afflicted with a high incidence of polydactyly (extra fingers or toes). The other person responds with the classic theological deflection: "The Lord works in mysterious ways." The second panel, labeled "Earlier...," shows an angel reporting to God that the Amish still refuse to masturbate, and God responding: "Time to send them some temptation."

The joke connects two real facts about the Amish community -- their strict sexual morality and their elevated rate of polydactyly (which is actually caused by the founder effect in their small, genetically isolated population) -- with an absurd theological explanation. The implication is that God gave the Amish extra fingers specifically to tempt them into masturbation, since more fingers might presumably make the act more appealing or novel. It is a classic SMBC irreverent theology joke, imagining God as a petty trickster who targets his most devout followers with cruelly specific temptations. The "mysterious ways" setup in the first panel is the standard religious non-answer that the comic gleefully undermines by providing a very specific (and very inappropriate) divine motivation.