Here is some great insight from J. Warner Wallace. He is a Dateline featured Cold-Case Detective, Senior Fellow at the Colson Center for Christian Worldview, Adj. Professor of Christian Apologetics at Talbot School of Theology, Biola University, author of Cold-Case Christianity, God’s Crime Scene, and Forensic Faith, and creator of the Case Makers Academy for kids.
I often wonder precisely when the disciples of Jesus realized their important role in Christian History. As these men sat at the feat of Jesus and listened to everything He had to say, did they realize they would someday testify to everything He said and did? Most eyewitnesses I’ve interviewed in my casework had no idea they would later be called into a jury trial to testify about what they heard or observed. As a result, they sometimes regret not paying better attention when they had the opportunity. But the disciples of Jesus had a distinct advantage over modern eyewitnesses in this regard. They were students of Jesus. Unlike spontaneous, unprepared witnesses of a crime, the disciples were desperately attentive to the words and actions of Jesus, and I imagine their attention to detail became even more focused with each miraculous event. For this reason, the authors of the gospels became excellent eyewitnesses and recognized the importance of their testimony very early.
While Jesus walked here on earth, His followers studied and learned from His actions and words. They were often mesmerized, confused and challenged by what they saw and heard. In spite of this, Jesus taught them and occasionally sent them out on their own. They memorized His teaching and relied on his wisdom when they weren’t with Him. We don’t know how much (if anything) these eyewitnesses wrote down during this time. Did the disciples take notes? Did they keep a journal? While Jesus was alive, the disciples likely felt no need to write down his words. The Word was witnessed in these incredible days, as men and women stood in awe of the Master, watching Him perform miracles and listening carefully to what He taught about God and eternal life.
During the first years following Jesus’s ascension, the apostles still may not have written immediately about Jesus. Why not? A careful reading of the Scripture will reveal a common theme: Many of the early authors of the New Testament expected Jesus to return before there would ever be a need for a multi-generational eyewitness record. They worked urgently to tell the world about Jesus, believing He would return to judge the living and the dead within their lifetime. In the days of the Apostles, the Word was heard, as the apostles preached to the world around them. But as the Apostles began to be martyred (and those who remained realized Jesus might not return in their lifetime), the need for a written account became clear. James, the brother of John was killed in 44AD (Stephen was killed even earlier), and not long afterward, the gospels began to emerge. The eyewitness gospel authors wrote down what they had seen so the world would have a record.