the shape of leadership

The Reliability of the Gospels

Answering today’s skeptics and critics

Craig Keener on October 23, 2019

As criticizing other people’s religion has become more acceptable in our culture, hostile critics of Christianity are stepping up their attacks against Jesus, with some radical popular skeptics denying even His existence.

Of course, denying His existence, or even the main elements of His ministry, is historically implausible. We have more accounts about Jesus, from within living memory of His ministry, than for almost any other ancient teacher.

Today most New Testament scholars agree on a number of key elements of Jesus’ ministry. For example, Jesus grew up in Nazareth, preached the Kingdom, taught in parables, was known by others for healing and exorcism, and was crucified under Pilate.

Nevertheless, skeptics’ questions challenge faith on the internet, in the media and in universities. Some of these questions arise even from scholars, though often speaking outside their disciplinary expertise. And while most New Testament scholars agree on a number of key elements of Jesus’ ministry, other details are more debated, depending on the particular scholar’s assumptions.

In this article, therefore, I will survey four reasons to believe that the Gospels are historically reliable, and address four common objections raised against their reliability. Most of these observations reflect research in my recent book, Christobiography: Memories, History, and the Reliability of the Gospels (Eerdmans, 2019).

Reasons to Believe

We have good reason to expect the Gospels to be historically reliable accounts. Calling them “reliable” does not suggest that the Gospels prove identical in all details or share identical perspectives, still less that after 20 centuries we can unearth evidence to support their every point. It does mean, where we can test them, the Gospels report real events and real teachings of Jesus, and that in them we genuinely meet Jesus.

The most accurate period of ancient biography was the period of the early Roman empire, precisely the period in which the Gospels were written. Further, the most reliable biographies were those about figures from within living memory of the biographer.

The Gospels’ overlap shows their dependence on and respect for sources. And finally, the Gospels retain elements that fit Jesus’ time and location better than those of the Gospels’ audiences.

1. Across the theological spectrum, most scholars today recognize the Gospels are ancient biographies. Among ancient types of prose literature, normally only biographies focused on single historical figures. The one exception was a fairly rare form of ancient novel, but the Gospels cannot fit that designation. Most ancient novels were romances — a feature lacking in the Gospels.

The rarer form of novels that dealt with historical figures never dealt with recent figures as the Gospels do; such novels usually referred to characters who lived centuries earlier. Moreover, these novelists were not interested in reporting genuine information. They generally made up most of their stories.

By contrast, the overlap among the Gospels shows that they depend on prior information. This is what we expect from ancient biographies. Biography had evolved from praise-or-criticism speeches centuries earlier into much more clearly historically based works by the first century.

Then as today, biographers wrote from particular perspectives and chose which information to emphasize and which information to omit. Nevertheless, they were not supposed to make up events like novelists did. They depended on prior sources, written or oral, that they believed conveyed accurate information.

By modern standards, the most historically based period of ancient biography starts in the first century B.C. (with Cornelius Nepos) and runs through at least the second century A.D. (with Plutarch, Suetonius and Lucian). Before and after that period, we encounter much more homiletical license. The Gospels, however, fortuitously come from the most historically based period of ancient biography.

2. The Gospels are from within living memory. Our best surviving biography of Alexander the Great comes from nearly five centuries after his death; Mark’s Gospel is usually dated to 34 to 45 years after Jesus’ death. Ancient historians and biographers freely admitted that when they recounted events from centuries earlier, they often had to depend on legends. The case was different, however, with figures from within the past generation or two, when they often could even interview witnesses.

Some people today question whether anyone would remember events in Jesus’ life by the time the Gospels were written. But while no one would claim that Jesus’ disciples remembered everything He said and did, they should have remembered more than enough to fill the Gospels.

Oral historians use the phrase “living memory” to refer to the period when people who knew the original witnesses might still be alive. After this period, legends are more likely to arise, although these legends often still contain information in condensed and packaged form.

Any Gospel written within the first century would be within living memory of Jesus’ ministry. A majority of scholars date all four canonical Gospels to the first century. All other so-called “gospels” are later than living memory — most of them centuries later.

Usually scholars date the Gospel of Mark to A.D. 64–75 (I prefer the earlier date), so roughly four decades after Jesus’ public ministry. If someone today suggested we cannot trust any witnesses’ claims about events that happened 40 years ago, we would not take them seriously. Most of us know someone (or are someone) who was around more than four decades ago.

Granted, we forget most experiences and certainly most details, but we do remember most particularly striking episodes. Presumably, many of Jesus’ miracles would qualify! Studies suggest that many events significant enough for us to remember after five years may stay with us even decades later, so long as our brains remain healthy.

Moreover, those who taught about Jesus were not simply modern Western consumers who can recheck our information on Google. They lived in a world that treasured memory. All our sources from the ancient Mediterranean world emphasize the importance of memory in education, from the elementary level up to the advanced level. Even today, in some parts of the world some Muslims who do not even understand Arabic can recite large parts of the Qur’an in Arabic from memory.

Disciples were learners at the advanced level. They were often in their late teens, one of memory’s most fertile periods. Teachers expected disciples to learn and pass on their teachings and example. This was true whether disciples were literate or illiterate, whether the instruction was in writing or oral. Unless Jesus’ disciples were highly unusual, we should expect them to have learned Jesus’ message and example thoroughly.

Not only would the disciples be expected to learn Jesus’ teachings, but they would regularly repeat them. As leaders in Jesus’ movement, they would recount these matters. Luke reports information passed down from “eyewitnesses and servants of the word” (Luke 1:2).

We can also be certain these stories circulated very widely in the first generation, making later alterations difficult. Luke writes that he is merely confirming the story of Jesus that Theophilus already knows (Luke 1:4). That does not leave Luke room to fabricate his story about Jesus.

3. The overlap shows their dependence on and respect for sources. By the time Luke writes, many others have written accounts about Jesus (Luke 1:1). We do not have all of Luke’s sources today, but one of them seems to be Mark (whose grammar Luke improves). Because Luke and Matthew overlap on many other points, but do not seem to have known each other’s accounts of Jesus’ birth or Judas’ death, most scholars also believe they share another source or sources in common.

One way we can test ancient biographies’ fidelity to their sources is to compare them with those sources where those sources have survived. Where Matthew, Mark and Luke overlap, we find them even closer to one another than was typical among ancient biographies. This means that Matthew and Luke were writing information-based works.

Since Matthew and Luke wanted to report information, this also means they believed that Mark and their other shared material were information-based. And since they wrote fairly soon after their sources, they were in a much better position to evaluate the quality of these sources than are we modern scholars, who are limited to guesswork.

Indeed, within living memory of Mark’s composition, a Christian writer named Papias claimed to have it on good authority that Mark wrote down stories he heard firsthand from Peter. Mark’s dependence on Peter would help explain why Matthew and Luke treated Mark’s Gospel as such an important source! John’s Gospel may depend less on Mark because John shared a stature similar to Peter’s (John 13:23-25, 20:2-8).

Ideally, historians today would love to interview the earliest available witnesses. Of course, we ordinarily cannot interview witnesses for events 2,000 years ago. Luke, however, was in a position to interview contemporaries. He recounts his thorough acquaintance with the matters he reports (Luke 1:3).

In ancient historical works, first-person claims were normally genuine claims to participation, so Acts suggests that Luke spent up to two years in Judea (Acts 21:17, 24:27, 27:1-2). This would have given him plenty of time to interview early witnesses (Acts 21:8,16,18).

4. The Gospels retain elements from Jesus’ time and location. When we preach or teach from the Bible, we often update parts of the story to help make it relevant to our audiences. Luke’s Gospel may do this, for example, when it presents a disabled man’s friends tearing off roof tiles (Luke 5:19) rather than digging through a roof (Mark 2:4). One might dig through many Galilean roofs, but Luke explains the scene in imagery more familiar to his northern Mediterranean audience.

Often, however, the Gospels retain earlier language or information simply because that is the way they knew the story. Thus, for example, Jesus’ favorite title for himself, “Son of Man,” is a Semitic figure of speech. It makes no more sense in Greek than it does in English.

Jesus uses many figures of speech that are attested among Aramaic-speaking Jewish teachers rather than in the Greek world. For example, both moving mountains and a large animal passing through the eye of a needle were figures of speech for doing something considered virtually impossible.

“To what shall I compare … ” was a common way to start a parable. Rabbis shared even such expressions as, “The measure you use is the measure you’ll get back,” and images such as someone with a log in his eye wanting to remove the splinter from another person’s eye (Matthew 7:1-3).

The Gospels report real events and real teachings of Jesus, and in them we genuinely meet Jesus.

Unlike Greeks, Jewish teachers commonly told story parables very similar to those of Jesus. Contrary to what some earlier scholars suggested, such parables often include interpretations, consistent with what we see in the Gospels.

Only local people called the lake of Galilee a “sea”; the Gospels preserve memory of the local title. Fishing was a common occupation there. No one outside of Galilee would have heard of Chorazin. Nor would they have heard of Nazareth, had Jesus not come from there (John 1:46). Bethsaida was renamed Julias about the year 30, after which it went by both names. The Gospels, however, use only the earlier name, depending on memories from Jesus’ time.

Answering Common Objections

Those who doubt the value of the Gospels for reliable pictures of Jesus typically raise objections against them. Most of these objections are easily answered — at least for those  believing in a God who performs miracles.

1. There are differences among the Synoptics. When I was a recent convert from atheism, attending an Assemblies of God church, I quickly noticed differences among the Gospels. These troubled me because I was expecting God to have inspired a Bible differently. Once I reached my second Gospel and Jesus got crucified again, I wondered, How often is this going to happen?

I did not understand that having separate accounts of ancient Christian biographers actually provides more evidence and inspired perspectives than we would get from one single account. Jesus did too many works for any one author (or even four) to record (John 21:25), so we could get only a selection of such accounts in any case.

Yet even eyewitnesses will not observe and recount all the same details. Moreover, ancient biographers did not write using the precise language of modern scientific manuals. We should not evaluate their reliability based on guidelines that no one could have expected, protocols that did not exist in their day. It is not the fault of the Gospels if critics ignore their historical context!

Ancient biographers had the freedom to recount stories in their own distinctive ways, with their own emphases. Such freedoms could reshape material. Compare, for example, Matthew’s “kingdom of heaven” in most places where Mark has “kingdom of God.” They could also rearrange material. Compare, for example, the different sequence of the fig tree cursing and temple cleansing in Matthew and Mark.

Biographies did not require chronological sequence. Such minor differences did not entail inventing events, and were an acceptable part of ancient biography. (For more on this, see Michael Licona, Why Are There Differences in the Gospels? [Oxford, 2017].)

The most conspicuous differences appear between John’s Gospel and the other three. The overlap in terms of events and kinds of events is considerable (the list in my book runs for several pages). Nevertheless, differences also abound, especially in the passion narrative. Here are some examples:

  • John omits the role of the disciples in Jesus finding a donkey (Mark 11:2; John 12:14).
  • John skips Jesus’ words about His body and blood and depicts Jesus as the Passover Lamb more directly (John 13:1, 18:28, 19:36).
  • In John, Jesus dips the bread and gives it directly to Judas (John 13:26) instead of Judas dipping it (Mark 14:20).
  • In John, Jesus rather than Simon carries Jesus’ cross (Mark 15:21; John 19:17).
  • Jesus’ final recorded cry in John sounds triumphant rather than pitiful (Mark 15:34; John 19:30).

Of course, Jesus probably did not utter only one statement from the cross. Moreover, prisoners normally carried their own cross, so it is likely that Jesus started carrying the cross. Still, John exhibits his own emphases as he recounts the story.

Is John trying to correct details in the earlier Gospels? Or is John simply using a storyteller’s surprise, tweaking some details in the traditional passion narrative for theological points? Because a pattern of changes emerges, John probably does the latter. If so, these are not mistakes, but deliberate emphases to make a point.

Scholars naturally compile entire books trying to explain the differences among the Gospels. What is most relevant here is that we observe such differences among ancient biographies more generally — and in fact often even among eyewitnesses today. The Gospels normally differ less among themselves than the Jewish historian Josephus differs with himself in his various accounts of the same events.

2. The Gospels include miracles. All four Gospels and Acts report miracles. The earliest sources of the Gospels report miracles, as does the eyewitness “we” material in Acts. So do the early church fathers. Moreover, the first-century Jewish historian Josephus reports that Jesus was not only a sage but a wonder-worker. Early critics of Christianity did not try to deny that Jesus performed wonders; they merely questioned their supernatural source.

The standard modern argument against biblical miracles is that we lack reliable witnesses for miracles today, so they probably did not happen back then, either. This objection, however, is no longer plausible. A 2006 Pew Research Center survey shows that hundreds of millions of people report witnessing divine healing.

Scholars have now published studies on global Pentecostal and charismatic healing with various academic publishers such as Oxford University Press, and the reports are not limited to Pentecostals. One might explain such claims in various ways, but clearly eyewitnesses offer them.

Some of these eyewitness reports involve dramatic healings, such as instant removal of blindness or resuscitation from the dead in the context of prayer. One study published in a medical journal in 2010 attests a number of people moving from blindness to sight and deafness to hearing immediately after prayer, in a sort of cutting-edge Kingdom setting analogous to the Gospels.

Although critics tried to dismiss the study, one of its authors provides further corroborating details in her 2012 book with Harvard University Press (Candy Gunther Brown, Testing Prayer). Moreover, millions of people have abandoned centuries of tradition to become Christians based on their experiences of miracles. One source within China attributed roughly half of all conversions to “faith healing” experiences.

As in the Gospels, such miracles flourish especially in areas of groundbreaking evangelism. Although many cases come from parts of the world where medical documentation is impossible, Global Medical Research Institute and others have published some case studies that do reflect dramatic healings without known natural explanations, even in the West.

3. The Gospels include demons. Although I am happy to stick my neck out for divine healing, I do not like to stick my neck out for demons. I do not like demons at all. Nevertheless, both Mark and the material shared by Matthew and Luke show Jesus delivering people from demons, and most scholars agree that Jesus’ contemporaries experienced Him as both healer and exorcist.

Deliverance from demonization continued in Acts and in the Early Church. Historians show that by the 300s, healing and exorcism were the main causes of conversion to Christianity.

Moreover, the sorts of possession and exorcism experiences noted in the New Testament are attested in a vast range of unrelated cultures around the world. Anthropologists have devoted countless books and essays to this subject. Nor can they be accused of religious bias.

A majority of the anthropologists who report these experiences do not believe in actual demons; they are simply reporting their observations of experiences that local participants attribute to spirits. Studies also show altered brain states during what anthropologists call “possession trance.” (I offer further discussion of healing and deliverance analogies in my book Miracles [Baker Academic, 2011].)

4. Jesus made predictions. Skeptics sometimes question accounts in the Gospels because they report that Jesus accurately predicted some then-future events, especially His own death and the temple’s destruction. Like secular dismissals of healings and exorcisms, simple dismissals of prophecy will carry little weight with Pentecostals. This skepticism simply assumes that such prediction is impossible, rather than offering evidence to that effect.

Granted that many of us have experience with errant or conditional prophecies, some prophecies are fulfilled dramatically. For example, over the years three different intercessors in Congo, who did not know each other, independently prophesied to Congolese Christian Médine Moussounga that she would someday marry a white man with a big ministry. She married me.

But even aside from the gift of prophecy, there were a few other Jewish people who expected the temple’s destruction, because they expected judgment against its corruption. Moreover, Jesus’ prediction appears in multiple different sources about Jesus, confirming its historical likelihood.

Certainly it was not invented by His followers, who continued to worship in the temple until the beginning of the Judean-Roman war. It appears not only in Mark but in some material shared by Matthew and Luke (Matthew 23:38; Luke 13:35), material circulating well before Jerusalem’s destruction.

Those who doubt that Jesus could have predicted His own death are on even shakier ground. Given the way things worked in the ancient world, there was no way that Jesus could have challenged the temple authorities by overturning the moneychangers’ tables and not expected to be killed. Granted, one could try to avoid this fate by raising an army or fleeing Jerusalem, but Jesus did neither. He did not simply predict His death; He provoked it.


Christians have strong reason to affirm the reliability of the Gospels. They are ancient biographies, from the most historically dependable period of ancient biography. They appeared within living memory of Jesus’ public ministry. Their overlap shows the authors intended to write information-based works, not novels. And the Gospels, though written to later audiences outside the Holy Land, preserve accounts that best fit Jesus’ earlier Galilean ministry.

We also have strong reasons to challenge the typical objections raised against the Gospels. Yes, there are differences among the Gospels. But these differences are the sorts of differences we expect among ancient biographies.

The Gospels offer different angles on the same Jesus. The Gospels report healings and exorcisms, but the impossibility of healings and exorcisms rests on presuppositions that Christians (and most faiths) reject. The Gospels report some predictions of Jesus that proved accurate, but this does not mean that the Gospels invented these predictions. Why not believe that Jesus was correct?

Historical analysis provides a common ground for discussion with non-Christians. Yet Christians have an additional and greater source of confidence in the Gospels, one not available to those who lack the experience of the Spirit. As John Calvin emphasized and Pentecostals agree, the Spirit testifies to Scripture’s inspiration.

We understand spiritual matters by spiritual means (1 Corinthians 2:13-15). Like the first apostles, we may preach boldly because the Spirit empowers us.

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