Why Should We Trust The Gospels?
I have sometimes heard individuals claim that the New Testament Gospels are not reliable sources for the life of Jesus. Ironically, some of these same individuals will claim that the 2nd or 3rd Century gospels somehow contain accurate Jesus traditions. The issue here is that the evidence shows just the opposite. The fact of the matter is that we have good reason to trust the canonical Gospels on the historical Jesus. As scholar F.F. Bruce nicely summarizes, "The evidence for our New Testament writings is ever so much greater than the evidence for many writings of classical authors, the authenticity of which no one dreams of questioning. And if the New Testament were a collection of secular writings, their authenticity would generally be regarded as beyond all doubt." This is true of the Gospels especially. So what are some of the reasons we have to accept the Gospels as reliable sources for the life of Jesus? Here are a few of these reasons:
1. The Canonical Gospels Were Written Early
The canonical Gospels were written incredibly early in comparison to many other works from antiquity. Other accounts claiming to have knowledge about the life of Jesus, such as the Gospel of Peter and the Gospel of Thomas, actually date to the middle to late second century, or perhaps even later than this, nearly 150 years after the events they claim to portray. By contrast, the canonical Gospels were written within 30-60 years of the events they describe. This is incredibly early in comparison to many of the other sources from antiquity. If we believe Josephus about the Jewish Wars, or that Tacitus got it basically right in his histories and annals, then we have no reason to think that the time gap between the composition of the Gospels and the events that they portray was so great that they could not accurately record them.
2. When The Canonical Gospels Were Written, Eyewitnesses Were Still Alive
Another reason to trust the Gospels is because, when they were written, eyewitnesses were still alive. They circulated in areas where there were eyewitnesses to what Jesus said and did. These eyewitnesses would have included both friendly and hostile individuals. If the Gospels got their information about Jesus basically wrong, we should expect to see another account contemporary with the Gospels correcting this. However, we see no such thing. Instead, what we do have record of are historical accounts outside of the Gospels that appear to confirm, not contradict, the main points about the life of Christ, such as his crucifixion.
3. The Gospels Were Written By Eyewitnesses Or Those Who Knew Eyewitnesses
One of the most significant facts about the canonical Gospels is that they were written by eyewitnesses or by companions of eyewitnesses. We have good reason to believe that, for example, Matthew wrote Matthew and John at least created the initial draft of John. Luke was a companion of Paul who claimed to have interviewed eyewitnesses. It is probable that Luke met with Peter and Mary at some point before the composition of his Gospel. Mark, as well, was a companion of both Peter and Paul, making it likely that he was able to record the memories of Peter. This is affirmed by a number of Church Fathers, such as Papias, Irenaeus, Justin Martyr, Clement of Alexandria, Tertullian, and Origen. Significantly, these affirmations of authorship come from a wide geographic distribution, and there is not an early, strong case made against Mark recording Peter's memories, as should be expected if this were disputed. The same can be said for Luke. Ultimately, however, this is not the only reason that we should believe that the Gospels are historically reliable. The point here is that the Gospels were written by people who would have known about Jesus first-hand, or had access to those who knew Jesus first-hand.
4. The Gospels Accord With Earlier Tradition About Jesus
The Gospels also accord with earlier traditions about Jesus. In several places, Paul seems to quote creeds or hymns of the early Church in his letters, and since his letters predate the Gospels, this is significant. Let me give one example of such early testimony. Embedded in 1 Corinthians 15:3-5 is an early creed of the Church. The creed itself may extend (with some exceptions) through verse 8, but there is little dispute about it extending through at least verse 5. In this creed, we discover a skeletal outline of what the earliest Christians believed about the death and resurrection of Jesus. The creed encapsulates several beliefs:
1. That Christ died
2. That his death was for our sins
3. That his death was "in accordance with the Scriptures"
4. That Christ was buried
5. That Christ was raised on the third day
6. That his resurrection was "in accordance with the Scriptures"
7. And that Christ appeared
The amazing thing about this creed is that most scholars date it to within approximately 5 years of the crucifixion (give or take a year or two, depending on which scholar you consult). Furthermore, the creed, if we are to understand it as extending through verse 8, contains Semitisms, which means that this was likely composed and spread in the very place where we should least expect such a thing to happen if there was solid evidence to counter what is claimed in this creed. Yet it did. As we study the creed here, we note the ways in which this creed aligns with the accounts in the Gospels. This strongly indicates that the authors of the Gospels didn't simply make this stuff up decades later. There is an early basis for this belief that likely originated, in my opinion, in or around Jerusalem.
5. The Internal Evidence For The Truth Of The Gospels Is Strong
Finally, what we read in the Gospels appears to match the cultural, social, political, and historical environment at the time. For example, what we read about the Pharisees, or the Herod family, or Pontius Pilate, or the Sanhedrin, or any number of other things that we could point to all match what we know historically from other sources. I want to be careful here. I am not arguing that, because the Gospels accurately portray Pilate, that therefore the miracles of Jesus happened. What I am arguing is that, if the authors of the Gospels got these basic facts correct, then this shows that they are generally reliable sources.
Beyond this, the Gospels contain several features that point to their accurate portrayal of the life of Jesus. One major aspect of this is that they did not leave out potentially embarrassing aspects of the life of Jesus. For example, Jesus is baptized by John. Yet John's baptism was a baptism of repentance. So why did Jesus need to be baptized? Someone who was making up a story about a sinless Savior would not likely have invented a scenario where that sinless Savior is baptized with a baptism of repentance from sin.
Let's look at another example. John the Baptist was supposed to be the forerunner of Jesus, according to the Gospels. Yet we read that John the Baptist had doubts about who Jesus was (Luke 7:18-23). Why would the authors of the Gospels invent a forerunner who doubts the person he is preparing the way for? Because this would have been potentially embarrassing to the early Church, it is likely not a fabrication.
At the end of the day, we have several good reasons to believe that the authors of the four Gospels give us an accurate account of the life of Jesus.
 F.F. Bruce, "The New Testament Documents: Are They Reliable?", p. 10