Over and over, John's gospel makes clear the hazard of taking Jesus literally. If you read through the the gospel, you may notice a pattern of Jesus saying things which are misunderstood when they are taken literally. This provides an opening for Jesus to speak at length on a particular subject. It happens with his "I AM the bread that came down from heaven" statement that happens a few verses before today's reading.
It happened with his "born again/from above" statement to Nicodemos a few chapters earlier, a word play that cannot be reproduced in English, or in Jesus' own Aramaic tongue for that matter. That deliberately confusing statement could only happen in Greek, which Jesus and Nic would not have been speaking. Turns out that the truth John's gospel hopes to convey is hard to find reading it literally or historically. The writer is perfectly happy to tell events that could not actually happen as told, and where Jesus says things that are impossible to understand unless you're reading the gospel from this side of Easter. His concerns are not with historical or literal accuracy.
I'm not entirely sure why this has caused such problems for modern day Christians. I suppose it grew out of an Enlightenment reverence for logic and scientific fact which imagined truth was a matter of getting all the details correct. (I'm unclear how this will change if the post-modern trend of thinking my opinion is more valid that facts continues.) Yet the Christians I've found most compelling, most Christ-like, are not the ones who are most certain of the facts (or their opinions). They are the ones who have hearts that are more expansive, more gentle, more loving than most. And while studying Scripture does help shape, refine, and direct such people's behavior, I don't think anyone's heart was ever enlarged simply by learning more facts.
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