John 3:6

That which is born of the flesh is flesh; and that which is born of the Spirit is spirit.

Just as there are two elements in the new birth, there are two elements in man that require it. The flesh is born of the water (baptized), and the spirit is born of the Spirit (receives the Holy Spirit); but these are not two births, only one new birth.

Born ... The etymology of this word bears witness to the nature of the ceremony of baptism, coming from an old Anglo-Saxon word, "to be drawn forth from."

The previous verse revealed the two elements of the new birth, this the requirement that both flesh and spirit participate in it. Thus, what Jesus was saying to Nicodemus was: "Do what my disciples have done; first submit to John's baptism, and then come join my company."[12] If he had done so, the second element of the new birth, the reception of the Spirit would have been completed after Pentecost. The fact that at that particular time, Nicodemus could not have received the Holy Spirit, since he was not given yet, proves that the new birth as experienced in the new dispensation was in view here. See under John 7:39.