I'm not saying baptism isn't important, but some can't get around their paradigm of associating "water" in
John 3 with water baptism. The original poster provided other plausible explanations of what "water" meant, but some can't see it, while others don't want to see it. I used to see that use of the word "water" as = water baptism. However, I now see "water" as the physical birth otherwise Jesus would have reiterated the water baptism later in the passage, but he only reiterated the spiritual rebirth/regeneration.