Let me admit my biases upfront. I believe in God and Jesus, but I’m definitely not a fundamentalist. In addition, current scientific knowledge does not support a role for the supernatural in the material world as we know it. You can read about my interpretation of Christianity in the post God the Programmer.
Some studies in alternative medicine journals show a slight enhancement of health through remote prayer, but most of these results only show very small improvements that in many cases can be explained away as examples of statistical chance or possibly examples of massaging the data. Even if remote intercessory prayer did work, the minimal effects shown in studies sympathetic to prayer suggest that a patient would be better off taking effective medications instead.
The following studies describe the disappointing results of prayer experiments in medical settings:
Are there demonstrable effects of distant intercessory prayer? A meta-analytic review. (Link)
Intercessory prayer and cardiovascular disease progression in a coronary care unit population: a randomized controlled trial. (Link)
Intercessory prayer in the treatment of alcohol abuse and dependence: a pilot investigation. (Link)
Pilot study investigating the effect of intercessory prayer in the treatment of child psychiatric disorders. (Link)
Science, medicine, and intercessory prayer. (Link)
Study of the Therapeutic Effects of Intercessory Prayer (STEP) in cardiac bypass patients: a multicenter randomized trial of uncertainty and certainty of receiving intercessory prayer. (Link)
The effects of intercessory prayer, positive visualization, and expectancy on the well-being of kidney dialysis patients. (Link)
The efficacy of distant healing for human immunodeficiency virus–results of a randomized trial. (Link)