Bayesian resurrection calculator

Adjust the dials yourself. Your prior is how probable you considered Jesus\' resurrection before looking at the evidence. For each piece of evidence, estimate how likely it would be if the resurrection happened and how likely it would be if it did not. The calculator applies Bayes\' theorem sequentially and shows how your belief should update. Follow the work of Timothy & Lydia McGrew (Blackwell Companion to Natural Theology).

Prior
1.00%
before any evidence
Cumulative Bayes factor
2.71e+7 : 1
evidence favors resurrection by this ratio
Posterior
> 99.99%
after the evidence
Your prior: P(Resurrection) before examining evidence
0.001%0.01%0.1%1%10%50%
Evidence you accept:
Jesus died by crucifixion
BF = 1.00
Independently attested across Christian, Jewish (Josephus), and pagan (Tacitus, Lucian) sources.
P(evidence | Resurrection)99.0%
P(evidence | No resurrection)99.0%
The tomb was found empty
BF = 6.47
Conceded even by the earliest Jewish counter-claim (Matt 28:11-15); ~75% of critical scholars accept it.
P(evidence | Resurrection)97.0%
P(evidence | No resurrection)15.0%
Multiple group appearances to the disciples
BF = 19.0
Rooted in the pre-Pauline 1 Cor 15 creed; group hallucinations are clinically unattested.
P(evidence | Resurrection)95.0%
P(evidence | No resurrection)5.0%
Paul's conversion (hostile witness) Top contributor
BF = 30.0
A dedicated persecutor becomes an apostle and is eventually martyred. Explained in his own letters.
P(evidence | Resurrection)90.0%
P(evidence | No resurrection)3.0%
James's conversion (skeptical brother)
BF = 17.0
Jesus' brother, previously unbelieving, becomes head of the Jerusalem church and is martyred (Josephus).
P(evidence | Resurrection)85.0%
P(evidence | No resurrection)5.0%
1 Cor 15 creed within 2-5 years
BF = 9.00
Even atheist Gerd Lüdemann dates the tradition to the first couple of years — too early for legend.
P(evidence | Resurrection)90.0%
P(evidence | No resurrection)10.0%
Women named as first witnesses
BF = 8.00
Criterion of embarrassment: nobody fabricating a story for a first-century audience would invent this.
P(evidence | Resurrection)80.0%
P(evidence | No resurrection)10.0%
Willingness of disciples to die
BF = 6.00
Best-documented cases (Peter, James son of Zebedee, James the brother, Paul) all die without recanting.
P(evidence | Resurrection)90.0%
P(evidence | No resurrection)15.0%
Step-by-step belief update
Start
Prior probability
1.00%
+ E1
Jesus died by crucifixion
+0.00%
1.00%
+ E2
The tomb was found empty
+5.13%
6.13%
+ E3
Multiple group appearances to the disciples
+49.25%
55.38%
+ E4
Paul's conversion (hostile witness)
+42.01%
97.38%
+ E5
James's conversion (skeptical brother)
+2.46%
99.842%
+ E6
1 Cor 15 creed within 2-5 years
+0.14%
99.982%
+ E7
Women named as first witnesses
+0.02%
> 99.99%
+ E8
Willingness of disciples to die
+0.00%
> 99.99%
P(R | all evidence) = > 99.99%

Tip: even a prior of 1 in 10,000 yields a posterior > 99% when the combined Bayes factor exceeds roughly 106.

What the math shows. When each piece of evidence is more expected on resurrection than on non-resurrection, the Bayes factors multiply. The McGrews argue the cumulative factor for the core resurrection evidence exceeds 1040, overwhelming any plausibly low prior. Even if you dial the likelihoods to far more conservative numbers than they propose, the posterior remains decisively in favor. The skeptical move has to be either rejecting the evidence or rejecting the method — not the math.
In Human Terms
How strong is a Bayes factor of 1040?
  • Forensic DNA identification evidence in court typically runs at about 1 in 109 to 1012. A cumulative factor of 1040 is about a trillion trillion times stronger than the DNA match that convicts a defendant beyond reasonable doubt.
  • Particle physicists declare a "discovery" at 5-sigma, about 1 in 3.5 million. 1040 is equivalent to roughly a 13-sigma result — the level at which physicists stop calling it evidence and start calling it the new baseline.
  • It is the Bayesian weight of guessing a specific atom in a kilogram of matter, blindfolded, on the first try — and the evidence here points that strongly toward one hypothesis.
Why priors can't rescue the skeptic
  • Suppose you think resurrection is so unlikely the prior is 1 in a billion (10-9). A Bayes factor of 1040 still leaves you with posterior odds of 1031 to 1 in favor.
  • To defeat this evidence with priors alone you would need to be more certain miracles are impossible than any human being is ever justified in being about anything — more certain than you are that the sun will rise, that other minds exist, or that you are not dreaming.
  • Hume's "no testimony is sufficient" argument is often quoted here — but Hume was arguing before Bayes' theorem was widely understood. Applied rigorously, his standard quietly demands a prior so extreme it is unreachable.
Put it together

If you would convict a stranger of murder on a 1012 DNA match, consistency requires you to take a 1040 cumulative case seriously. Either the ordinary standards of evidence apply here too — or you are making an exception precisely because of what the evidence points to.

Interactive tool by Christwise. Adjust the dials to see how the evidence shifts a posterior belief.Read the full lesson