Yes, I think virtually every argument reduces to something like this: The Holy Spirit broadcasts God's Truth to all of humanity. I don't know why I hear and understand it so clearly while you are getting a garbled message, but....
I am not sure that all arguments really reduce to that. For instance, a Guru might point out the amount of time and discipline which disciples devote to pursuing understanding-(albeit, they would probably use some wise parable).
Rabbi's might note the years of discussion and study which they pursue
Catholics and other more traditional Christian Religions might suggest "some hear a calling and answer that calling" and understand only through that calling, study, and devotion.
While some of the newer Christian religions who articulate a personal relationship with God, might say that you have to put away logic and reason in order to take the leap of faith. This leap is based not on thought but on feeling and trust. Thus, they might suggest that your logic and reason are the reasons for what you hear.
I certainly understand what you are saying. There is no rational reason to take any holy book as Truth. Every single one, has potential flaws.
No sacred text will likely ever serve one exactly as it does another. Yet, at some juncture, someone in our history did indeed painstakingly take the time attempting to document and preserve that which lies within these texts. For linguistic reasons alone, many of these texts are invaluable. But more to the point, when you read these texts you read stories which certainly have themes still relevant today. Who cares whether Jonah was in a whale or whether Shiva has four arms. Who cares whether the Roman Guards or Mary Magdalene or some pauper first saw Jesus after he was resurrected.
If I were to find out that there was a textual mistranslation and there were really four witches in MacBeth or If I were to find out that Odysseus fought twenty Cyclops, I do not think that I would discard the entire story.
If you are looking for problems within these texts then that is all you are likely to find within them. If you are looking for meaning then you will likely find that. And in the case of your friends, if you are looking for a confirmation of your belief you will likely find that.
I think a more interesting way to look at interpretations is through just listening. Since that which we discover is usually just a facet of our self, listening to your friends interpretations might not help you know your friends' god or God or gods or Gods better, but it could very well help you know your friend.