Unless you are born of water and of the spirit, there is no chance that you can enter the kingdom of heaven” (John 3:3, 5). Or simply, only those who are born again will see the kingdom of God.
A struggle is involved in birth, which is why it is referred to a labor. In ancient times, giving birth would often take the mother’s life. It is a struggle for the baby to be born. Even so in spiritual things, the spiritual new birth is a painful work.