D.A. Carson: The question is important, because it lies at the heart of Jesus’s explanation of “born again,” of new birth, of regeneration. When Jesus first introduces the category (John 3:3), Nicodemus clearly doesn’t understand what Jesus means (3:4 NIV): “How can someone be born when they are old?” he asks. “Surely they cannot enter a second time into their mother’s womb to be born!” Many people think the question Nicodemus poses shows that he is a rather dimwitted literalist. But that’s almost certainly too harsh. You don’t get to be called “the teacher of Israel” (John 3:10—possibly a title) if you can’t spot the odd metaphor. When he hears Jesus say that to enter the kingdom one must be “born again,” I suspect Nicodemus understands Jesus to mean that we are not good enough to enter the kingdom: we must start over, have a different origin, spring from a different life. Nicodemus thinks Jesus is going too far: people
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