Beyond the Biblical gospels: comparing Luke and Romans using mathematical models

Thanks to all for your patience while I enjoyed the holidays with lots of family time and remarkably little blogging or research. :)

In this post we take our next step with the mathematical models, and it begins to show different kinds of results. To this point we have been looking at the Bible's four gospels: Matthew, Mark, Luke, and John. To expand our horizons a little, the next document I'd like to consider is Paul's letter to the Romans. It is an early letter within the Christian church, it has been vital in the formation of Protestant Christianity. In modern times the question has become more pointed: Did Paul stay with the direction laid out by Jesus, or was Paul responsible for a change of course? I will not presume to answer that question here, but I will point out some promising pieces of objective information that come to light with this kind of mathematical review.

To compare this letter to a gospel, then, I chose the Gospel of Luke. Since Luke was a companion of Paul's, I thought it could be a productive place to begin.

The Short Version of the Results

Shared Word Estimate (13/52) = 25%
Shared Emphasis Estimate: 27%

Much Different than Gospel-to-Gospel Comparisons

For the first time, all of the matching methods show less than a 50% match -- and here the match is significantly less than 50%. While the gospels consistently had a shared emphasis estimate higher than 50%, Paul's letter to the Romans matches Luke at roughly half that level.

There are several kinds of differences that are immediately seen. We will start at the top of the list with the most common word. The gospels all had the same word as the most common word: Jesus. The letter to the Romans has a different most-common word: God. In fact, "Jesus" doesn't appear until #8 on the list in Romans. However, "Christ" appears higher on the list than "Jesus".

What do we make of the fact that "Jesus" is the common way to speak of Jesus in the gospels, but "Christ" is more common in Paul's letter to the Romans? The word "Christ" does not appear on the common-words list of any of the four Biblical gospels. To be sure, even if the word "Christ" is not prominent in the gospels, still the idea that Jesus is the Christ is well-known from the gospels. They all make a point to explain that Jesus is the Christ, and to demonstrate it. In the gospels, the time when Peter identifies Jesus as the Christ is portrayed as a key teaching, and so is the moment at Jesus' trial where the political leaders ask whether Jesus is the Christ. The Gospel of John even explains that the reason the book was written is "that you may believe that Jesus is the Christ". So the concept of "Christ" is an important idea in the gospels, even though the word is not used often. We could say that calling Jesus by the title "Christ" shows the next stage of logical development after those gospel accounts. That is, calling Jesus "Christ" shows a prior acceptance of those teachings about Jesus. It is, in a way, summary-level talk, to call Jesus by the title of Christ. The gospels are interested in explaining and demonstrating that Jesus is the Christ; for the epistle to the Romans, this has already been explained to the readers' satisfaction and is now part of the foundation on which they build. So here we have a new kind of difference: a difference about the level of detail being used or the logical progression of ideas, whether something is demonstrated or already given. It is a difference in the level of the conversation, and in the starting point of the discussion.

But to what extent is it discussing the same subject matter? The action from the gospels, the physical settings and the people who first heard Jesus are not a large part of the picture in Paul's letter. The book of Romans does not commonly speak of "crowds" and "disciples", or "Peter" and "Mary", or "Jerusalem" and the "house", or "asked" and "answered" in the way that the Gospel of Luke commonly does. The actions from Jesus' life are not being narrated in his letter; the letter is a different type of material. Paul does have some interaction with people in his letter, but he interacts with the people that he expects to read his letter. So while there is no "crowd" in Paul, instead we have Paul's trademark where "greet" is on the common word list in Romans, and there is a small crowd reading the letter. (Anyone who reads a few of Paul's letters will notice that he spends a certain amount of time on personal greetings. We know many early Christians by name because Paul greeted them by name in his letters.)

Still, the differences go deeper. The gospels are all biographies, or we might say the fourth gospel is a memoir and reflection on Jesus' life. As records of Jesus' life, all four gospels share the same most common word: "Jesus". The letter to the Romans, on the other hand, has "God" as the most common word, then "sin" and "law". To be sure, "sin" and "law" are discussed in the gospels -- but not always enough to make the most-common-words list. For "sin" we may remember conversations about sins being forgiven. For "law", there are records of discussions between Jesus and other people over the interpretation of the law. Questions come up about matters of divorce, or tax, or ritual hand-washing, or which are the most important commandments, or a case of capital punishment, or whether certain religious leaders could claim that Jesus was morally in the wrong for performing miracles to heal people on the Sabbath, as it was a kind of work. So "sin" and "law" both have a presence in the gospels, either directly or by example. Paul discusses these ideas at a summary level, where "sin" and "law" are often abstractions. The same might be said of "faith" and "grace". These words are commonly used in Romans where Paul discusses them in a relatively abstract way. In the gospels these same words "faith" and "grace" are not often used directly, but are instead shown in living action.

But the major differences are not limited to the fact that Paul is more abstract, while the gospels show Jesus in action. By Paul's leading words in Romans ("God", "law", "sin"), we see Paul also trying to put Jesus in a context that his readers might know. He explains Jesus against a background familiar to his fellow Jews, back in his day when the Temple still stood in Jerusalem and sacrifices were still offered daily, where people made pilgrimages for the Torah's decreed feasts, where Torah-based Jewish legal courts had some degree of legal authority and might have jurisdiction over some cases, where someone might comment publicly about a lack of morals if someone failed to perform a ritual washing before a meal, where breaking the Sabbath might lead to a formal legal inquiry. We see Paul struggling with the question: For a Jew like him or many of his readers -- learning that Jesus is the Messiah and that the Messiah is about God's love, about grace and mercy, about good news and life -- what does that mean for their old understanding of law and sin? What does that mean for their ideas about righteousness before God?

We also see Paul spending some effort discussing "Jews" and "Gentiles", "Israel" and being "circumcised". What does it mean that even Gentiles are now included in a new covenant with God? What does it mean that Gentiles have a righteousness before God that did not come from the Law of Moses? What does that mean for whether the Law of Moses should apply to Gentiles? On the one hand, if the Gentiles do not need to be circumcised to be in the New Covenant, then is circumcision still relevant? On the other hand, if Gentiles are now numbered among God's chosen people -- which previously had meant Israel -- then is there still any advantage in being a Jew? Paul considers the implication that God has made a covenant for all people through Jesus; and Paul seems to have something of an identity crisis on what it means to be Jewish now, in light of God opening the gate wide to all nations. For him and his concept of his beloved Jewish nation's role in the world, it is not an easy transition to go from being an only child to being firstborn among many. This emphasis raises the question: to what extent was the letter to the Romans about universal themes for all people of all times, and to what extent was that letter meant to speak to the existential crisis of Judaism that Paul saw in God's new covenant for all nations? (In a few places Paul seems defensive of the special role of his people, and mentions several times that things are "first for the Jew" and then for the Gentile. I should mention that Paul's letter to the Romans is not the only philo-Semitic writing in the New Testament. I have become curious whether anyone has actually studied the philo-Semitism of the New Testament. In my readings through the materials, philo-Semitism seems far more prominent than any supposed "anti-Semitism", which is not surprising since most of the authors were themselves Jewish.)

A few advantages of the mathematical comparisons

• We may be able to determine whether something is rightly a classified as a "gospel" by whether it is mainly focused on Jesus. It may also matter whether the action/narration words, setting, and character names are still in a prominent place. 
• We may be able to tell that a document is "next generation" material (from a logical point of view) if it starts by assuming that Jesus is the Christ, as shown by a high usage of the word "Christ" compared to "Jesus".
• We may need to look for relationships between key words -- like between "Jesus" and "Christ" -- where the difference shows that a historically earlier viewpoint is now taken as "given".
• To interpret the findings correctly, we may need to look for detail v. summary types of differences, or specifics compared to abstractions, like Jesus' kind encounters with various people as opposed to Paul's mention of "grace" or "mercy".
• The details of the differences between two documents can show, objectively, where the focus of an author lies and bring out themes that might be missed otherwise.