Reminding people of death strengthens their belief in social and moral progress, especially when those people aren’t very religious. In our time, a growing number of people has substituted genuine religious experience for a belief in progressive politics. But history warns us. Decades after Karl Marx called religion “the opiate of the people”, Soviet Premier Vladimir Lenin declared war. Although the majority of twentieth century Russians were religious, Lenin and his successor Stalin waged two decades of anti-religious campaigns against their own people, killing millions.