Final answer:
The three reasons for believing the apostle John wrote the Gospel bearing his name are traditional attribution by early Church history, internal textual evidence of an intimate knowledge of Jesus' life, and the symbolic association of the eagle with John reflecting the spiritual depth found in the Gospel.
Step-by-step explanation:
The questions regarding who wrote the Gospel of John, and the reasons for believing John to be the author, are rooted in historical, textual, and tradition-based research. There are three conclusive reasons supported by scholars and historical evidence for believing that the apostle John wrote the Gospel bearing his name.
The traditional attribution of the Gospel to John stems from early Church writings and testimony claiming that John, one of the original disciples of Jesus, was the author.
- Evidence within the Gospel itself points to an author with an intimate knowledge of Jesus' life, which suggests a close associate or disciple like John. This is supported by the manuscript's detailed eyewitness descriptions of events.
- Symbolic aspects, such as the eagle associated with John in early Christian iconography, reflect the spiritual depth and theological insight found in the Gospel, characteristics believed to be indicative of the apostle John's perspective.
These factors combined—the traditional accounts, internal textual evidence, and symbolic identifiers—provide a strong basis for the scholarly acceptance that the apostle John is indeed the author of the fourth Gospel.