Having found that religion and charity go hand-in-hand, Robert Putnam and I sought to understand why. The answer might surprise you. We initially thought that religious beliefs must foster a sense of charity—whether inspiration from biblical stories like the Good Samaritan or, perhaps, a fear of God’s judgment for not acting charitably. However, we could find no evidence linking people’s theological beliefs and their rate of giving—which also helps to explain why the “religion effect” varies little across different religions. The rates for charitable giving according to the Jumpstart survey are: 61 percent of Black Protestants; 64 % of Evangelical Protestants; 67 % of Mainline Protestants, 68 % of Roman Catholics, and 76 % of Jews. By contrast, only 46 % of the not religiously affiliated made any charitable giving.

Rather than religious beliefs, we found that the “secret ingredient” for charitable giving among religious Americans is the social networks formed within religious congregations. The more friends someone has within a religious congregation, the more likely that person is to give time, money, or both, to charitable causes. In fact, even non-religious people who have friends within a religious congregation (typically, because their spouse is a believer) are highly charitable—more so than strong believers who have few social ties within a congregation.