Nicodemus answered him, "How can these things be?"
There are those who say the water refers to the Word of God. As Peter in his first epistle, chapter l, verse John 3:23 , said that we've been "begotten unto this living hope through the Word of truth." And so, we've been born again through the Word of God. And Jesus said in John l5, "Now you are clean through the Word which I have spoken unto you." And so it is being born of the Word of God. And, the theological giants have taken their positions and there are those who say water baptism and those who say born through the Word God, and they write their commentaries and their ideas and thoughts and blast each other's ideas.