Undesigned Coincidences is a Cumulative Case for the Historical Reliability of the Bible

The argument from Undesigned Coincidences is a cumulative case for the historical reliability of the Bible (specifically the Gospels and the Book of Acts). It suggests that when two or more independent writings "interlock" in a way that seems accidental or unintended, it provides strong evidence that the authors were recording eye-witness testimony of actual events.

The argument focuses on instances where one account contains a detail that raises a question, which is then answered—often in passing—by a completely different account. The key is that these connections are:

• They don't look like they were "planted" to make the stories match.

• The details are typically trivial and unrelated to the main theological point of the passage.

• One text provides the "missing piece" to a puzzle found in another.

Examples

Feeding the 5,000:

• In John 6:5, Jesus asks Philip where to buy bread. Why Philip? He wasn't the most prominent apostle.

• Luke 9:10 mentions the miracle happened near Bethsaida. 

• John 1:44 (in a different context) notes Philip was from Bethsaida. Philip would have known the local bakeries.

The Accusation:

• During Jesus' trial in Matthew 26:61, witnesses claim he said, "I am able to destroy the temple of God." Matthew never records him saying this earlier.

• John 2:19 records Jesus saying this years earlier at the start of his ministry. The two accounts independently preserve the saying and the later "twisted" accusation.

The Green Grass:

• Mark 6:39 mentions the crowd sat on "green grass." Why was the grass green in a mostly arid region?

• John 6:4 mentions the Passover was near. Passover occurs in the spring, the only time of year that region is lush and green.

It is much harder for a forger to create dozens of tiny, cross-document puzzles than to simply make the stories identical. If the authors were simply copying each other, the "puzzle" and the "answer" would likely be in the same book. The fact that they are split suggests they are drawing from a shared reality.

Proponents like Lydia McGrew and Tim McGrew argue that these coincidences are precisely what we find in modern cold-case investigations when multiple witnesses tell the truth from different perspectives.

Common Criticisms Refuted

1) Critics suggest that Author B simply read Author A and filled in the gaps. Proponents argue this is highly unlikely for several reasons:

• Many coincidences are so subtle that they went unnoticed for centuries until scholars pointed them out. If an author were "fixing" a story, they would make the connection obvious so the reader actually sees the correction.

• Often, the "answer" is found in a passage that has nothing to do with the "puzzle." 

• If Mark were copying Matthew, it would be strange for him to delete the very detail that makes his own story make sense.When we look at later apocryphal texts (like the Gospel of Peter), we see the opposite: the authors go out of their way to smooth out the narrative and explain every detail. The canonical Gospels leave the seams showing, which is a hallmark of raw reporting.'

2) Critics say if you look at any two books long enough, you'll find patterns.

• A single coincidence might be a fluke, but the argument relies on a massive, cumulative collection of them. It’s like a forensic investigation: one piece might be coincidence, but twelve different pieces pointing to the same person across a crime scene constitute proof.

• Proponents don't just feel a connection exists. They look for specific criteria: a) the detail must be incidental (not the point of the story), b) non-obvious, and c) explanatory.

• You can test this by trying to find similar "undesigned coincidences" in known fictional works or the aforementioned apocryphal gospels. Generally, you don’t find them because fiction writers don’t accidentally leave behind pieces of a puzzle they didn't know they were creating.

3) Critics argue that proving "green grass" doesn't prove "walking on water." Proponents argue this misses the point of the Witness Character:

• If a witness is consistently accurate and scrupulous about tiny, throwaway details (like local naming patterns or specific geography), it increases the probability that they are telling the truth about the big things. It moves them from the category of myth-maker to eyewitness.

• If the authors were part of a grand conspiracy to invent a religion, why would they be so careful to get the names of 1st-century Judaean villagers right, but then lie about the Resurrection? Usually, people lie for a benefit; if they are truthful in the details that don't benefit them, they are more likely to be truthful in general.

• The argument isn't meant to be a silver bullet for the supernatural. Instead, it’s a foundation builder that establishes the Gospels as historical documents rather than late-stage legends.