As is the case with so many people in the Bible, there may be a little confusion as to who St. John is. He might not be the person who wrote the gospel named for him -- maybe it was someone else by the same name. Or someone else entirely, who knows?
Another person he might not be is the Beloved Disciple -- that person, who is never named, is designated as the BD only in the gospel of John, and the popular reasoning has always been that he must be the author himself, modestly refraining from identifying himself by name. Who knows?
He also might not have written the Book of Revelation or the three little letters named for him and might never even have heard of the island of Patmos, let alone lived there -- parts of those books seem to arise from a time after John the disciple lived. Unless he lived a very, very long time.
Does this trouble you, this uncertainty about the specifics? Does it seem to call the whole religious enterprise into question, if we don't know all the facts? Can't even control the chain of evidence for our own sacred books?
It's okay. There is more than one way to read the Bible. There is much more to it than just the things that happen in it. There is even more to it than the context and the intention of its writers -- the beginnings of things aren't the whole of them: I don't know the whole story of your marriage just because I attended your wedding. Stuff happened after that. Some of it was known by many: the children you had, where you lived. Other things were known to you alone. Some things in your marriage were not as they appeared from outside it. And some things looked different years after they happened, even to you, from the way they looked when you were going through them.
The Bible is like that. It is alive, even now, old as it is. The Bible isn't just its writers -- the Bible is also its readers. It always has been. We bring ourselves to it when we read it. We interact with it. We even argue with it, as one does with the living and cannot do with the dead.
It is said that St. John once drank a cup of poisoned wine and was none the worse for having done so. You won't find that in the Bible -- it's a story that came along later, one of those tales you are liable to hear at a family gathering or at a wake, one of those stories that get a little more interesting with each telling. Perhaps they are not facts, but that doesn't make them lies.
What they are is stories. Ponderings. Poems, even -- take another look at the opening of the fourth gospel. Read them for what they are. Let them remind you of things in your life, or of things you wish were in your life. Let them make you wonder who God is, what it meant to whoever penned the lines that God loved the world enough to give an only Son for it, and what it might mean for you today. Let it mean nothing or everything, but tell your truth as you see it now, and then strive to remain open to your own growth and change.
More than that we cannot do.