For the faithful, the Bible is the word of God; for the historian it is not since there are major discrepancies among gospels. For example, the genealogy of Jesus differs among the gospels of Mathew and Luke. Also in Mark, the followers don’t recognize him as the Messiah until much later while in John, it is right from the beginning. There is no agreement even on which day he actually died. Mark says one thing and John says something else.
Can we know for sure if the gospels contain the sayings of Jesus? We can’t be sure since the gospels disagree there too. In John for example, Jesus asserts his divinity, which he never does in the synoptic gospels. But then isn’t it possible that the anonymous authors of the gospels re-contextualized the messages and edited them to suit their needs? Isn’t it sufficient that Jesus’s theology of the Kingdom of God, was something prevalent in that period?
If the Gospel writers changed words — the historian would argue — would they differ radically in important events like the trial of Jesus by Pilate or the words he uttered during crucifixion or the post-death events? In Mark he asks the Father why he was forsaken while in Luke he asks his killers be forgiven.
The believer would then say that even though there are some differences, they all agree on where Jesus lived, preached and how he died. The historian would posit that there is no eyewitness account of Jesus outside the gospels. The first Jewish reference appears in Josephus, six decades later; the first Roman reference almost nine decades later in Pliny.
How do you resolve this dispute? You can get some answers by organizing a debate between a non-believer and a believer. And that’s what happened at the Midwestern Baptist Theological Seminary in April of this year where Dr. Craig Evans and Dr. Bart Ehrman debated on questions like ” are the gospels historically reliable?” and “Do the gospels contain eyewitness tradition?”. You can see the entire debate here and read few accounts here and here.