Bible Reliability / Answer across Scripture
The Gospels share one witness to Jesus while each writer arranges, emphasizes, and explains material for a particular purpose.
The Gospels have different details because each Gospel writer tells the story of Jesus with a particular purpose, audience, arrangement, and emphasis. Difference does not automatically mean contradiction, and harmonizing too quickly can keep readers from hearing each Gospel's own voice. A context-first approach reads Matthew, Mark, Luke, and John both together and separately, asking what each author is showing about Jesus.
Luke explains that he writes an ordered account, while John says he selects signs so readers may believe. The question belongs where each Gospel gives a distinct witness to the same Jesus without requiring every account to be written in the same shape.
Luke 1:1-4 and John 20:30-31 are purpose statements. They show that the Gospels are not random memories; they are ordered, purposeful testimony written so readers can understand and believe.
Key passages
1Because many have undertaken to draw up a narrative concerning those matters which have been fulfilled among us,
2even as they delivered them to us, who from the beginning were eyewitnesses and ministers of the word,
3it seemed good to me also, having traced the course of all things accurately from the first, to write to you in order, most excellent Theophilus;
4that you might know the certainty concerning the things in which you were instructed.
30Therefore Jesus did many other signs in the presence of his disciples, which are not written in this book;
31but these are written, that you may believe that Jesus is the Christ, the Son of God, and that believing you may have life in his name.
One mistake is to assume differences must be errors. Another is to erase each Gospel's distinct theological and literary purpose by harmonizing too quickly.