Scientific Evidence for Answered Prayer and the Existence of God
by Rich Deem


New Prayer Study

The newest prayer study is a meta-analysis that takes into account the entire body of empirical research on intercessory prayer (17 major studies). The new study showed that according to American Psychological Association Division 12 criteria, intercessory prayer is classified as an experimental intervention that, overall, shows a small, but significant, positive effect.1

Rich Deem

What scientific evidence do we have that God exists? Most skeptics would say "none." A crucial doctrine of Christianity is that God listens to and answers prayers. So why not test this doctrine scientifically, using a double-blind, clinical trial? This is the exact premise that groups of medical doctors used in double-blind "drug" studies of the efficacy of Christian prayer on healing. Papers are available online.

A Report on the Papers:

  1. "Positive Therapeutic Effects of Intercessory Prayer in a Coronary Care Unit Population"2
  2. "A Randomized, Controlled Trial of the Effects of Remote, Intercessory Prayer on Outcomes in Patients Admitted to the Coronary Care Unit"3
  3. Effects of remote, retroactive intercessory prayer on outcomes in patients with bloodstream infection: randomised controlled trial.4

1. "Positive Therapeutic Effects of Intercessory Prayer in a Coronary Care Unit Population"


Cardiac patients from the San Francisco General Medical Center were randomly divided (using a computer-generated list) into two groups. The names of the patients in the "test" group were given to a group of Christians, who prayed for them while they were in the hospital. The intercessory prayer team members were chosen on the following basis:

  1. Born again Christians on the basis of John 3:35
  2. Led an active Christian life on the basis of
    1. daily devotional prayer
    2. fellowship in a local Christian church

The "placebo" group received no prayer. Neither the "test" nor the "placebo" group of patients knew if they were receiving prayer. Likewise, the hospital staff, doctors, or nurses were "blinded" since they did not know which patient belonged to which group.


Statistics were acquired from the prayer and placebo groups both before and after prayer, until the patients were discharged from the hospital. There were no statistical differences between the placebo and the prayer groups before prayer was initiated. The results demonstrated that patients who were prayed for suffered "less congestive heart failure, required less diuretic and antibiotic therapy, had fewer episodes of pneumonia, had fewer cardiac arrests, and were less frequently intubated and ventilated." Statistics demonstrated the the prayer group had a statistically significantly lower severity score based upon the hospital course after entry (p < 0.01). Multivariate analysis of all the parameters measured demonstrated that the outcomes of the two groups were even more statistically significant (p < 0.0001). In science, the standard level of significance is when a "p value" is less than 0.05. A value of 0.01 means that the likelihood the result is because of chance is one in 100. A p value of 0.0001 indicates that in only one study out of 10,000 is the result likely to be due to chance. Table 2 from the study is reproduced below. The remarkable thing which one notices is that nearly every parameter measured is affected by prayer, although individually many categories do not reach the level of statistical significance due to sample size. However, multivariate analysis, which compares all parameters together produces a level of significance seldom reached in any scientific study (p < 0.0001). The author points out that the method used in this study does not produce the maximum effect of prayer, since the study could not control for the effect of outside prayer (i.e., it is likely many of the placebo group were prayed for by persons outside of the study). It is likely that a study which used only atheists (who had no Christian family or friends) would produce an even more dramatic result. However, since atheists make up only 1-2% of the population, it would be difficult to obtain a large enough sample size.

TABLE 2. Results of Intercessory Prayer

Study Variable

Days in CCU after entry 2.0 � 2.5 2.4 � 4.1 NS
Days in hospital after entry 7.6 � 8.9 7.6 � 8.7 NS
Number of discharge medications 3.7 � 2.2 4.0 � 2.4 NS

New Problems, Diagnoses, and
Therapeutic Events After Entry

% (No.)

% (No.)

Antiarrhythmics9(17)13 (27)NS
Coronary angiography9 (17)11 (21)NS
VT/VF7 (14)9 (17)NS
Readmissions to CCU7 (14)7 (14)NS
Mortality7 (13)9 (17)NS
Congestive heart failure4 (8)10 (20)<0.01
Inotropic agents4 (8)8 (16)NS
Vasodilators4 (8)6 (12)NS
Supraventricular tachyarrhythmia4 (8)8 (15)NS
Arterial pressure monitoring4 (7)8 (15)NS
Central pressure monitoring3 (6)7 (15)NS
Diuretics3 (5)8 (15)<0.01
Major surgery before discharge3 (5)7 (14)NS
Temporary pacemaker2 (4)1 (1)NS
Sepsis2 (4)4 (7)NS
Cardiopulmonary arrest2 (3)7 (14)<0.01
Third-degree heart block2 (3)1 (2)NS
Pneumonia2 (3)7 (13)<0.01
Hypotension (systolic <90 torr)2 (3)4 (7)NS
Extension of infarction2 (3)3 (6)NS
Antibiotics2 (3)9 (17)<0.01
Permanent pacemaker2 (3)1 (1)NS
Gastrointestinal bleeding1 (1)2 (3)NS
Intubation/ventilation0 (0)6 (12)<0.01

NS = P > .05; VT/VF = ventricular tachycardia or ventricular fibrillation

2. "A Randomized, Controlled Trial of the Effects of Remote, Intercessory Prayer on Outcomes in Patients Admitted to the Coronary Care Unit"


Cardiac patients from the CCU at the Mid America Heart Institute (MAHI), Kansas City, Mo, were randomly chosen and assigned to control or prayer groups. In this study, patients were not told about the prayer study and doctors did not know which patients were assigned to which groups. According to the paper, "The intercessors represented a variety of Christian traditions, with 35% listing their affiliations as nondenominational, 27% as Episcopalian, and the remainder as other Protestant groups or Roman Catholic. Unlike the Byrd study, the intercessors of the MAHI study were given no details about the medical conditions of the patients, but were only given their first name.


The main table of results, reproduced from the study appears as Table 3 below. Because of the small sample size of each individual component, only one of the individual components reached statistical significance. However, the overall effect was statistically significant, with a P value of 0.04, meaning that the result was likely to occur by chance in only 1 out of 25 times the experiment was repeated.

Table 3. Effects of Intercessory Prayer on Individual Components of the Mid America Heart Institute–Cardiac Care Unit (MAHI-CCU) Score*
No. (%) of Patients
MAHI-CCU Score Component Usual Care Group
(n = 524)
Prayer Group
(n = 466)
Antianginal agents59 (11.3)47 (10.1).62
Antibiotics82 (15.6)77 (16.5).77
Unstable angina4 (0.8)1 (0.2).38
Arterial monitor42 (8.0)32 (6.9).57
Catheterization180 (34.4)162 (34.8).94
Antiarrhythmics56 (10.7)50 (10.7).94
Inotropes76 (14.5)69 (14.8).96
Vasodilation78 (14.9)59 (12.7).36
Diuretics112 (21.4)97 (20.8).89
Pneumonia10 (1.9)12 (2.6).62
Atrial fibrillation17 (3.2)12 (2.6).66
Supraventricular tachycardia6 (1.1)2 (0.4).29
Hypotension7 (1.3)8 (1.7).82
Anemia/transfusion66 (12.6)50 (10.7).42
Temporary pacer16 (3.0)13 (2.8).95
Third-degree heart block1 (0.2)2 (0.4).60
Readmit to cardiac care unit22 (4.2)25 (5.4).48
Swan-Ganz catheter172 (32.8)123 (26.4).03
Implanted cardiac defibrillator6 (1.1)10 (2.1).32
Electrophysiology study15 (2.9)10 (2.1).61
Radiofrequency ablation8 (1.5)2 (0.4).11
Extension of infarct2 (0.4)0 (0.0).50
Gastrointestinal bleed12 (2.3)5 (1.1).22
Interventional coronary procedure155 (29.6)121 (26.0).21
PTCA alone69 (13.2)62 (13.3).95
PTCA with stent and/or rotablator86 (16.4)59 (12.7).10
Permanent pacer21 (4.0)12 (2.6).28
Congestive heart failure17 (3.2)19 (4.1).60
Ventricular fibrillation/tachycardia12 (2.3)10 (2.1).95
Intra-aortic balloon pump20 (3.8)12 (2.6).36
Major surgery76 (14.5)51 (10.9).11
Sepsis7 (1.3)7 (1.5).96
Intubation/ventilation27 (5.2)26 (5.6).88
Cardiac arrest6 (1.1)5 (1.1).84
Death46 (8.8)42 (9.0).99
* PTCA indicates percutaneous transluminal coronary angioplasty.

3. Effects of remote, retroactive intercessory prayer on outcomes in patients with bloodstream infection: randomised controlled trial.

This study involved 3393 patient subjects whose bloodstream infection was detected at the hospital from the years 1990�1996. Remote, retroactive intercessory prayer was said for the well being and full recovery of the intervention group. Results were measured through mortality in hospital, length of stay in hospital, and duration of fever. Mortality was reduced in the intervention group (28.1%) compared to the control group (30.2%) although the difference did not reach statistical significance. However, length of stay in the hospital and duration of fever were significantly shorter in the intervention group than in the control group (P = 0.01 and P = 0.04, respectively). According to the author of the study:

"Remote, retroactive intercessory prayer said for a group is associated with a shorter stay in hospital and shorter duration of fever in patients with a bloodstream infection and should be considered for use in clinical practice."

Implications of the studies

Obviously, science has demonstrated in three separate studies the efficacy of Christian prayer in medical studies. There is no "scientific" (non-spiritual) explanation for the cause of the medical effects demonstrated in these studies. The only logical, but not testable, explanation is that God exists and answers the prayers of Christians. No other religion has succeeded in scientifically demonstrating that prayer to their God has any efficacy in healing. In fact, studies that have used intercessors from multiple religious backgrounds have failed to prove the efficacy of prayer.6 The Bible declares that Jesus Christ has power over life and death and sickness and is able to heal us, both physically7 and spiritually.8 He gave this power to His disciples and those who follow Him.9

2006 American Heart Journal study

A widely publicized study from 2006 failed to show the efficacy of intercessory prayer. However, the design of the latest study was somewhat unusual.10 The researchers used three patient groups. Two groups were advised of the study, but were not told whether they were in the prayer group or placebo group. The third group knew that they were being prayed for. The study was performed at six hospitals. Out of 3295 eligible patients, 1493 (45%) refused to participate, which is very high, although they did not explain the reasons for non-participation. The intercessors were composed of three groups. Two were Roman Catholic and one was a Protestant group (Silent Unity, Lee’s Summit, MO). Unlike in previous studies, the intercessors were not allowed to pray their own prayers. The prayers were given to them by the study coordinators to "standardize" the prayers. The discussion section of the paper suggested that at least some of the intercessors were dissatisfied with the canned nature of the prayers. In attempting to standardize prayer, I believe the study introduced a serious flaw, since most intercessors tend to pray as they are led by the Spirit, instead of praying prepared scripts. Jesus told His followers not to pray repetitiously, since God would not hear those kinds of prayers.11

Ultimately, the results showed that groups 1 (prayer) and 2 (no prayer) were identical, whereas group 3 (those who knew they were being prayed for) did worse than the other two groups. The lack of efficacy of intercessory prayer in this study could be due to theological problems with the study design.

References Top of page

  1. Hodge, D.R. 2007. A Systematic Review of the Empirical Literature on Intercessory Prayer. Research on Social Work Practice 17: 174-187.
  2. Byrd, R.C. 1988. Positive Therapeutic Effects of Intercessory Prayer in a Coronary Care Unit Population. Southern Medical Journal 81: 826-829. [online paper]
  3. Harris, W.S., Gowda, M., Kolb, J.W., Strychacz, C.P., Vacek, J.L., Jones, P.G., Forker, A., O’Keefe, J.H., and McCallister, B.D. 1999. A Randomized, Controlled Trial of the Effects of Remote, Intercessory Prayer on Outcomes in Patients Admitted to the Coronary Care Unit. Arch Intern Med. 159:2273-2278. [PDF version]
  4. Leibovici, L. 2001. Effects of remote, retroactive intercessory prayer on outcomes in patients with bloodstream infection: randomised controlled trial. British Medical Journal, 323, 1450-1451 .
  5. Jesus answered and said to him, "Truly, truly, I say to you, unless one is born again, he cannot see the kingdom of God." (John 3:3)
  6. Krucoff, M. W., et al. 2005. Music, imagery, touch, and prayer as adjuncts to interventional cardiac care: the Monitoring and Actualisation of Noetic Trainings (MANTRA) II randomised study. Lancet 366:211-217.
  7. And Jesus was going about in all Galilee, teaching in their synagogues, and proclaiming the gospel of the kingdom, and healing every kind of disease and every kind of sickness among the people. (Matthew 4:23)
    And Jesus was going about all the cities and the villages, teaching in their synagogues, and proclaiming the gospel of the kingdom, and healing every kind of disease and every kind of sickness. (Matthew 9:35)
  8. "But in order that you may know that the Son of Man has authority on earth to forgive sins," He said to the paralytic. (Mark 2:10)
    and He said to them, "Thus it is written, that the Christ should suffer and rise again from the dead the third day; and that repentance for forgiveness of sins should be proclaimed in His name to all the nations, beginning from Jerusalem. (Luke 24:46-47)
  9. And He called the twelve together, and gave them power and authority over all the demons, and to heal diseases. And He sent them out to proclaim the kingdom of God, and to perform healing. (Luke 9:1-2)
  10. Benson H, Dusek JA, Sherwood JB, Lam P, Bethea CF, Carpenter W, Levitsky S, Hill PC, Clem DW Jr, Jain MK, Drumel D, Kopecky SL, Mueller PS, Marek D, Rollins S, Hibberd PL. 2006. 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. Am. Heart J. 151:934-942.
  11. "And when you are praying, do not use meaningless repetition as the Gentiles do, for they suppose that they will be heard for their many words. (Matthew 6:7)
Last updated March 18, 2007


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