Religions seem to defy the law-of-demand, which suggests that all else equal, an increase in the cost of an activity will induce individuals to decrease the resources they spend on that activity. Rather than weakening religious organizations, evidence shows that the sacrifices exacted by religious practices are positively associated with the success of those organizations. We present the first strong evidence that this association is neither spurious nor endogenous. We use a natural experiment that rests on a peculiar time-shifting feature of Ramadan that makes the fasting duration—our measure of sacrifice—vary not just by latitude but from year-to-year. We find that a half-hour increase in fasting time during the median Ramadan day increases the vote shares of Islamist political parties by 11 percent in Turkey’s parliamentary elections between 1973 and 2018, and results in one additional attendee per 1,000 inhabitants for voluntary Quran courses. We further investigate two mechanisms, screening and commitment, that could explain the effects we find. By testing their divergent implications, we infer that commitment is the mechanism triggered by sacrifice, which drives up the intensity of religious beliefs and participation that in turn bolster the success of religious organizations.

宗教似乎违反了需求法则，这表明在其他条件相同的情况下，一项活动成本的增加将促使个人减少他们在该活动上花费的资源。证据表明，宗教实践所要求的牺牲与这些组织的成功呈正相关，而不是削弱宗教组织。我们提出了第一个强有力的证据，表明这种关联既不是虚假的也不是内生的。我们使用了一个基于斋月特殊时间变化特征的自然实验，它使得禁食持续时间——我们衡量牺牲的标准——不仅因纬度而异，而且逐年变化。我们发现，在 1973 年至 2018 年期间的土耳其议会选举中，斋月中位数的禁食时间增加半小时会使伊斯兰政党的投票份额增加 11%，并导致每 1,000 名居民增加一名自愿参加古兰经课程的人。我们进一步研究了两种机制，筛选和承诺，这可以解释我们发现的影响。通过测试它们的不同含义，我们推断承诺是由牺牲触发的机制，它提高了宗教信仰和参与的强度，进而促进了宗教组织的成功。