Scholars of history apply various tests to ancient documents to establish their historical reliability. When these tests are applied to the gospels, they stand head and shoulders above any comparable early writings as a document to be seen as reliable history. They were written close in time to the events of Jesus' life and those of the early church. A comparison of the large number of early copies of the original manuscripts means we can be confident that what we read today is what was originally written. Moreover, the fact that these copies were dispersed throughout the world during the first centuries means we can be sure there was no systematic alteration of what was written. This would only be possible if all the copies could be consistently changed at one time.
Other historical writings confirm what is recorded too at many points. And the gospel writers themselves stress that they are recording historical events based on eye-witness accounts. The spread of their beliefs depended on their reputation of accuracy and honesty, and they had nothing to gain by writing what they did except persecution and death. It is therefore extremely unlikely they lied, not least because people were around when the gospels were first published to verify or challenge their assertions.Most compelling here is the fact that the gospels just don’t read as if they’ve been fabricated. They don’t always portray the founders of early Christianity in the best light, and do not shirk saying things that could have got the writers into trouble.
(Luke 1:1-4, John 21:24-25, Acts 2:22)