The nature of “proof” in historical contexts, especially regarding events and documents from the ancient world, operates differently from empirical proof as understood in the natural sciences. The question of whether the Gospel writers were actual eyewitnesses to the events they describe, particularly the resurrection of Jesus Christ, is addressed through historical criticism, textual analysis, and considerations of early Christian tradition.

1. Internal Evidence: The Gospels themselves contain various claims and hints of being based on eyewitness testimony. For example, the Gospel of John makes explicit claims to eyewitness testimony (John 19:35, John 21:24). Luke’s Gospel begins with an assertion that the author has carefully investigated everything from the beginning and decided to write an orderly account for Theophilus, so that he might know the certainty of the things he has been taught (Luke 1:1-4).
2. External Evidence: Early Christian writings outside the Bible provide some support for the traditional authorship of the Gospels. For instance, Papias of Hierapolis, an early Christian bishop and a hearer of John, is quoted by Eusebius as saying that Mark’s Gospel was based on Peter’s teachings and that Mark carefully recorded the eyewitness accounts of Peter. Similarly, church fathers like Irenaeus, writing in the late 2nd century, attribute the Gospels to their traditionally named authors and sometimes describe their connections to eyewitnesses.
3. Scholarly Analysis: Scholars debate the reliability and dating of the Gospels, with some arguing that the Gospels were written too late after the events they describe to be direct eyewitness accounts. Others, however, note the presence of eyewitness-type detail in the narratives and argue for earlier dating that would allow for direct eyewitness input. The use of sources, oral traditions, and the practices of ancient historiography are all considered in these analyses.
4. Archaeological and Historical Corroboration: While not proof of eyewitness authorship, archaeological findings and historical research have corroborated various details in the Gospels, lending credibility to their overall historical context and, by extension, to the possibility of their being based on eyewitness testimony.

Ultimately, the question of proof for the eyewitness nature of the Gospels rests on the convergence of these lines of evidence and the criteria one uses for historical reliability. Faith perspectives also play a significant role in how this question is answered, with many believers accepting the traditional claims of eyewitness testimony as a matter of faith, informed by the internal and external evidences that align with their convictions.

The Gospels of Matthew, Mark, Luke, and John serve as the primary sources for the life, teachings, death, and resurrection of Jesus Christ within the Christian faith. The traditional view held by many throughout Christian history is that these works were written by direct disciples or associates of Jesus, thus providing a form of eyewitness testimony, especially to the events surrounding the resurrection.

Matthew is traditionally attributed to the apostle Matthew, a tax collector who became one of Jesus’ disciples. This Gospel is seen by some as an eyewitness account due to Matthew’s close association with Jesus.

Mark is traditionally said to be the work of John Mark, a companion of both Peter (one of the twelve apostles) and Paul. Early church tradition, as recorded by Papias in the second century, suggests that Mark’s Gospel was based on Peter’s eyewitness accounts, making it one step removed from a direct eyewitness.

Luke, the author of both the Gospel of Luke and Acts, was a physician and companion of Paul. He explicitly states in the introduction to his Gospel (Luke 1:1-4) that he carefully investigated everything from the beginning, relying on the accounts of “those who from the first were eyewitnesses and servants of the word.” Thus, while Luke’s Gospel is not an eyewitness account itself, it claims to be based on such accounts.

John’s Gospel is traditionally attributed to John the apostle, the “disciple whom Jesus loved.” It presents itself as an eyewitness account, particularly noted in John 21:24: “This is the disciple who testifies to these things and who wrote them down. We know that his testimony is true.”

While modern biblical scholarship often examines and debates these traditional attributions, considering issues of historical context, textual analysis, and the transmission of oral traditions, the Gospels are nonetheless valued within Christianity for their theological insights and moral teachings, as well as their accounts of the life of Jesus, including his death and resurrection. The belief in their connection to eyewitnesses, whether direct or once removed, has been a foundational aspect of their authority for many believers.