Tumour

Religion is like a brain tumour. In some people it just sits inside the skull, if not benign then at least mostly harmless, causing merely the odd hallucination, the odd irrational thought, the performance of the odd meaningless ritual. In others though it erupts into malignancy, destroying not just the individual but many human beings around them, or, at best, causing the domination of other human beings and the determination to control every aspect of their lives.