However we choose to define depression, both its frequency and its disruption of normal life are staggering. The World Health Organization named depression the second most common cause of disability worldwide after cardiovascular disease, and it is expected to become number one in the next ten years. In the United States, 5 to 10 percent of adults currently experience the symptoms of major depression (as previously defined), and up to 25 percent meet the diagnostic criteria during their lifetime, making it one of the most common conditions treated by primary care physicians. At any given time, around 15 percent of American adults are taking antidepressant medications.

Studies of religious groups, from Orthodox Jews to evangelical Christians, reveal no evidence that the frequency of depression varies across religious groups or between those who attend religious services and those who do not. So in a typical congregation of 200 adults, 50 attendees will experience depression at some point, and at least 30 are currently taking antidepressants.