Some scholars have urged that the authorship of this Gospel does not matter greatly. We do not have the information to determine the point, they say, and in any case it is of no great importance. It is not who wrote the words that counts, but what he wrote. There is something to this. It is certainly the case that the important thing is that we heed what is said, and, further, that this is more urgent than indulging in scholarly arguments about authorship. It is also true that the Gospel as it stands is anonymous. Even the most conservative among us need not feel bound to espouse any particular view of authorship. But the subject is not unimportant, for all that. If we can feel that there are good grounds for thinking of an eyewitness, and specifically of John the Apostle, as being behind this Gospel, our view of it will be one thing. But if we see it as written by a second-century Christian who had never set eyes on Jesus, it will be quite another. While complete certainty may be unattainable, the question is one that we may discuss to our profit.
Morris, L. (1995). New International Commentary on the New Testament. The Gospel according to John (p. 4). Grand Rapids, MI: Wm. B. Eerdmans Publishing Co.