Regeneration is not an esoteric doctrine. It is not something we are allowed to postpone discussion of until later. It is the sine qua non of being able to discuss anything later. If a man is not born again, he will not be able to see the kingdom, much less sit down in that kingdom to learn the things that Jesus said were so far beyond us now.Italics original.
This is because when we are born again, a dramatic miracle happens. When we are born again, we are turned into people.