Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

This comic depicts a post-apocalyptic scenario where survivors worship an atomic bomb as a god, with a monument labeled "GOD" built around a nuclear warhead. A traveler questions this, pointing out that atom bombs destroyed the world -- they are the reason civilization is gone, everyone is sick, and the crops are dead. The worshiper simply confirms "Yes."

When the traveler asks what is for dinner, the worshiper replies "Jello and snack cakes" -- processed foods that would be among the few things to survive a nuclear apocalypse. The traveler immediately shouts "All hail the bomb!" The joke is that the availability of preserved junk food in a world where all natural crops have died is enough to convert someone to worshiping the very weapon that caused the destruction. It satirizes how easily people can be won over to irrational belief systems when those systems provide tangible immediate benefits, no matter how absurd the underlying logic.