Struggle and the fear of death turn people to religion. Among men who received a draft letter calling them to fight in the Vietnam War, their gravestones were vastly more likely to contain religious imagery—crosses, the Magen David, etc.

Even the men who merely expected to receive a draft letter became a bit more religious, perhaps out of a fear of what might happen if they went. But, to be sure, let's look at a negative control: Women who would've been drafted had they been men were not made more religious.

This effect was very robust. Religiosity did not set in among those who died prior to the lottery, and the effect held across racial, regional, and political lines.

This result sort-of replicated today. Using the International Social Survey Program, researchers found that - Wars - Economic depressions Boost religious attendance.