In the mid-second century AD, a Christian theologian named Tatian created a work called the Diatessaron (meaning “out of four” in Greek), in which he attempted to harmonize the four Gospels into one single narrative. However, in order to create this harmony, Tatian had to leave out certain passages and details to make it all fit together in one coherent package.

And Christians ever since have attempted to do the same thing with the four Gospels. This process called harmonization is when you compare accounts of the same story in the Gospels to come up with plausible explanations of how the accounts can all fit together. 

But is this how we are supposed to read the Gospels?

Reading the Gospels Vertically Vs. Horizontally

Another way of thinking about this issue is reading the Gospels vertically versus horizontally. To read a Gospel vertically is to read it from top to bottom (beginning to end) just like you would any other book. In contrast, to read horizontally is to read the same accounts side-by-side, comparing and contrasting the similarities and differences. 

Let’s look at the story of Jesus cleansing the temple to help us see how the two methods work. This story takes place in all four Gospels: Matthew 21:12-17, Mark 11:15-19, Luke 19:45-48, and John 2:13-16.

If you only read the Gospels of Matthew, Mark or Luke vertically, you would think that Jesus cleansed the temple once towards the end of his ministry. However, if you only read the Gospel of John vertically, you would think that Jesus cleansed the temple once at the beginning of his ministry. 

Then interpreters came along and asked, did Jesus cleanse the temple at the beginning of his ministry like it says in Matthew, Mark, and Luke, at the end of his ministry like it says in John, or twice? In order to answer this question, you must compare the accounts horizontally.

Harmonizing Can Be Dangerous

I think there can be a time and a place to read the Gospels horizontally. However, I also think there are some significant dangers that we can run into when our primary focus is to harmonize every detail of the four Gospels into one “meta-story.”

Let’s look at two of these possible dangers.

1. Danger #1: Losing the Gospel’s Voice

The first mistake we can make is to neglect reading the Gospels as individual books altogether. One of the first things I learned in Bible college was that each Gospel was written by a different author for a specific reason to a specific audience. As a result, each author displays unique writing and storytelling characteristics. Therefore, we must let each Gospel author speak independently to notice their unique style, vocabulary, and purpose!

To demonstrate this, let’s return to the cleansing of the temple. Mark seems to indicate that the temple cleansing event was one of the first dominoes to fall that ultimately led to Jesus’ crucifixion: 

“And the chief priests and the scribes heard this, and they began seeking how to put Him to death; for they were afraid of Him, because all the crowd was astonished at His teaching” (Mark 11:18).

When you read John’s account, however, the main ramification of this event is that many people started to believe in him:

“Now when He was in Jerusalem at the Passover, during the feast, many believed in His name as they observed His signs which He was doing” (John 2:23).

You could easily miss or downplay these details if you didn’t let the Gospel writers tell their own stories in their own way. However, reading John vertically will lead you to ask important questions such as:

• What purpose does the temple cleansing story serve in John’s Gospel? 
• What other signs did Jesus do in the Gospel that resulted in people believing in him? 
• How does the story fit within the overall structure of John’s Gospel?

2. Danger #2: Changing, Adding or Omitting Details of an Account

A second danger in harmonizing multiple Gospel stories is that we can easily modify, add, or omit important details of one account to make it fit our harmonization. How far are you willing to go when you cannot make certain details match up together in a coherent way? 

Returning to the Diatessaron, I actually think Tatian did a really good job with his harmony of the Gospels. However, if you read the beginning sections recounting Jesus’ birth, you will notice something very important missing from Matthew and Luke’s accounts: the genealogies of Jesus. 

That’s right, Matthew 1:1-17 and Luke 3:23-38 are nowhere to be found. It makes you wonder if Tatian couldn’t get the genealogies to quite fit together so he decided to leave them out altogether! I would venture to say, though, that Matthew and Luke had reasons for including the genealogies of Jesus in their Gospels, and that omitting or ignoring them is not a wise move.

Why You Should Read the Gospels Vertically

I think our primary approach should be to read each Gospel in its entirety, study its own background, structure, themes and so on. After all, they were written as individual works in the first place!

In a similar way, I think it’s okay to compare Paul’s theology between his letters, but only after each letter has been understood individually. It is only after you have studied the background, themes, purpose and so on of a letter that you could rightly contrast it with another. If you didn’t do this first, then it would be easier to take a theological point in Romans, read that theology into a passage in Galatians, and then miss the point Paul is trying to make in Galatians!

At the end of the day, God didn’t give one massive Gospel; He gave us four. He didn’t give us one giant book; he gave us an entire library of books from different time periods and genres. So I encourage you to allow each Gospel to speak for itself. If you do harmonize the Gospels, don’t change, add, or omit something from a Gospel so that it fits your harmonization.

Read the Bible primarily the way God gave it to us: one book at a time.