Dr. Harold KoenigDr. Harold G. Koenig is co-director of the Center for Spirituality, Theology, and Health at Duke University Medical Center, where he also serves on the faculty as Professor of Psychiatry and Behavioral Sciences, and Associate Professor of Medicine. Dr. Koenig is the author of many books, including "The Healing Power of Faith," "Faith and Mental Health," and "Spiritual Caregiving," and he has been nominated twice for the Templeton Prize for Progress in Religion. He spoke with us recently about why he believes being part of a religious community can make people healthier—and happier.

recent study suggests that praying for others does not improve their health. How do you interpret the results?

I think the results are very consistent with good science and good theology. Good science because there's no acceptable scientific mechanism or pathway by which prayer—at least the way it was designed in this study without people knowing whether or not they were prayed for—could have any effect, and it's good theology because God is not predictable, he's not a part of the material universe.

It tells us nothing about the effectiveness of prayer.

Do you think it's impossible to do that?

It's impossible for studies designed like this. God would have to be quantitative and predictable, which is ludicrous in the context of any Christian or Jewish or Islamic tradition and even within the Eastern traditions.

How do you measure God's will for a person? Ninety-six percent of the participants in the Harvard study had someone else praying for them. We don't know how much prayer they had, we don't know how sincere the prayers were. None of that was taken into account, and it would be very hard to measure those things. And none of the benefits to the prayed-for group were measured after 30 days. Maybe God healed them after 30 days—we don't know. You can see that this study is ridiculous.

Putting aside the ability to be able to prove it or not, do you believe that prayer can heal—specifically help someone, for example, recover from cancer?

Absolutely. I believe that on faith and I also believe it because I've seen that happen with people, including personal friends. Of course they knew they were being prayed for, by their families and their churches, and those people have had remarkable recoveries. I believe it because it says it in the scriptures that I believe in. So there's no doubt in my mind that prayers help people—those who are prayed for and those saying the prayer.

One thing we do know is that God is good and because God is good, whatever God allows to happen or does in response to prayer has to be good. Theologically speaking it may be bad for a person to do well after coronary artery bypass surgery. It may be that if a person had some complications, he would realize his limitations, he may reach out to God, he may forgive his neighbor, he may tell his loved one that he loves them. Good things come out of difficult situations.

Would you distinguish between the effectiveness or the power of intercessory prayer (praying for others) and people praying for themselves?

I think for the person who is praying, that praying for someone else is better than praying for him/herself. It may give you comfort to know that God is listening, so I would encourage people to pray; but if you're praying for someone else that's like a prayer one step above, because that means you're concerned about the benefit of that other person, which is something which, according to the scriptures, you're rewarded for.

So if you want to be healthy you should pray for others?

Pray for others, pray for yourself, and don't worry about these crazy studies. Faith is evidence of things not seen. If you could reliably predict the effectiveness of prayer, you wouldn't need faith, because you'd have proof.

Beyond the effects of prayer, do you believe religious practice can lead to other health benefits? What are they?

Bear in mind that these benefits are not intended, they're kind of a consequence of going to church or praying or reading the Bible or being religiously committed. They're kind of a side effect of being religious for more valid, more intrinsic reasons.

The benefits of devout religious practice, particularly involvement in a faith community and religious commitment, are that people cope better. In general, they cope with stress better, they experience greater well-being because they have more hope, they're more optimistic, they experience less depression, less anxiety, and they commit suicide less often.

They don't drink alcohol as much, they don't use drugs as much, they don't smoke cigarettes as much, and they have healthier lifestyles. They have stronger immune systems, lower blood pressure, probably better cardiovascular functioning, and probably a healthier hormonal environment physiologically—particularly with respect to cortisol and adrenaline [stress hormones]. And they live longer.