When God told Moses, “I have made a covenant with you and with Israel,” He thereby made every person in Israel a covenant participant (Exodus 34:27). No person had a choice in how God defined the covenant. After the covenant was ratified, there was no choice about membership: To be born an Israelite was to be
in the covenant. Eight days after birth, baby boys were circumcised— marked as belonging to the covenant nation (Leviticus 12:3). This mark went back to God’s earlier covenant with Abraham.
He who is eight days old among you shall be circumcised. Every male throughout your generations, whether born in your house or bought with your money from any foreigner who is not of your offspring, both he who is born in your house and he who is bought with your money, shall surely be circumcised. So shall my covenant be in your flesh an everlasting covenant. Any uncircumcised male who is not circumcised in the flesh of his foreskin shall be cut off from his people; he has broken My covenant. (Genesis 17:12-14)
However, when the New Covenant approaches, we find something entirely new and different: Birth into Abraham’s family is becoming irrelevant. Listen to John the Baptizer and Jesus speak to Jewish leaders who trusted in their nationality.
When he [John the Baptizer] saw many of the Pharisees and Sadducees coming to his baptism, he said to them, “You brood of vipers! Who warned you to flee from the wrath to come? Bear fruit in keeping with repentance. And do not presume to say to yourselves, ‘We have Abraham as our father,’ for I tell you, God is able from these stones to raise up children for Abraham.” (Matthew 3:7-9)
[Jesus said,] “Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. Do not marvel that I said to you, ‘You must be born again.’” (John 3:5-7)
Flesh gives birth to flesh (John 3:6). In other words, your earthly parents passed on earthly life to you, but they were not the source of spiritual life. To live with God in His kingdom, you must be born in the new way of water and Spirit.
You must be born again—born of water and Spirit.