“Neither in my private life nor in my writings,” Sigmund Freud wrote in a 1938 letter to Charles Singer, “have I ever made a secret of being an out-and-out unbeliever.” Indeed, he wrote to Marie Bonaparte, “I regard myself as one of the most dangerous enemies of religion.”

And, in fact, he was plainly obsessed with religion, treating it repeatedly in such books as “Totem and Taboo” (1913), “The Future of an Illusion” (1927), “Civilization and Its Discontents” (1930) and “Moses and Monotheism” (1938), comparing the “wishful illusions” of religion to “blissful hallucinatory confusion,” religious teachings to “neurotic relics,” and religion itself to “a universal obsessive compulsive neurosis” and “a childhood neurosis.”

And this theme of religious faith as psychological defect, a sickness of the mind, remains popular among modern atheists, too. “Faith,” declares Richard Dawkins in “The Selfish Gene” (1976), “seems to me to qualify as a kind of mental illness.” “It is difficult to imagine a set of beliefs more suggestive of mental illness,” agrees Sam Harris in his 2004 bestseller “The End of Faith,” “than those that lie at the heart of many of our religious traditions.”

So, are religious people by definition “sick”? Mentally ill? Is atheism healthier than faith?

For four decades, Armand Nicholi, a clinical professor of psychiatry at Harvard Medical School as well as the editor and co-author of the “Harvard Guide to Psychiatry,” has taught an honors course for Harvard College and Harvard Medical School that’s focused on Freud and the great Christian writer C.S. Lewis. Although the two never actually met — Freud died in 1939 at age 83 while Lewis died at 64 in 1963 — Nicholi puts them in dialogue and comparison with each other. (This isn’t as arbitrary as it might seem: Lewis, an atheist for half his life, was well aware of Freud’s writings.)

In 2002, based upon that course, Nicholi published “The Question of God: C.S. Lewis and Sigmund Freud Debate God, Love, Sex and the Meaning of Life.” It’s a fascinating study, and one could easily argue from it that Lewis led a healthier and happier life than did Freud.

Harold Koenig, a psychiatrist on the faculty of Duke University, has established himself, via such publications as “Is Religion Good for Your Health? The Effects of Religion on Physical and Mental Health” (1997), his “Handbook of Religion and Mental Health” (1998), and his editorship of the Oxford “Handbook of Religion and Health” (2012), as a premier authority in this area. He and his collaborators argue that religious involvement is correlated with better mental health in the areas of depression, substance abuse and suicide, and, somewhat less certainly, with better results in the treatment of stress-related disorders and dementia.

Moreover, according to Tyler VanderWeele, professor of epidemiology at Harvard University, recent research published by himself and his colleagues in the Journal of the American Medical Association’s JAMA Internal Medicine and JAMA Psychiatry and in the Annals of Behavioral Medicine confirms the links that previous scientific investigation had identified between attendance at religious services and enhanced health. Regular attendance is associated, for example, with “a roughly 30 percent reduction in mortality over 16 years of follow-up; a five-fold reduction in the likelihood of suicide; and a 30 percent reduction in the incidence of depression,” VanderWeele wrote in “Does Religious Participation Contribute to Human Flourishing?” at bigquestionsonline.com.

But the apparent blessings don’t end there: Regular participation in communal religious worship appears to be associated with “greater likelihood of healthy social relationships and stable marriages; an increased sense of meaning in life; higher life satisfaction; an expansion of one’s social network; and more charitable giving, volunteering, and civic engagement,” VanderWeele wrote.

One might perhaps conclude that it’s the social support afforded by religious participation that confers such benefits. VanderWeele, however, says that social support accounts for only about 20-30 percent of the measured results. The self-discipline encouraged by religious faith and the optimistic worldview that it supports also appear to be important contributing factors to physical health and longevity.

Of course, none of this proves religious claims are true. But it does strongly suggest that faith isn’t an illness, and that, on that point at least, Freud and his followers are wrong. As Isaiah 40:31 promises, “they that wait upon the Lord shall renew their strength; they shall mount up with wings as eagles; they shall run, and not be weary; and they shall walk, and not faint.”

Daniel Peterson teaches Arabic studies, founded BYU’s Middle Eastern Texts Initiative, directs MormonScholarsTestify.org, chairs mormoninterpreter.com, blogs daily at patheos.com/blogs/danpeterson, and speaks only for himself.