Jesus’ response to Nicodemus was an ultimatum. Be born again, or miss out on the Kingdom of God (v. 3). Nicodemus, the smart man that he was, seemed a little confused by this idea, as do many people in our day.
While Nicodemus mentions it, Jesus never addresses the idea of natural childbirth. Instead, He focuses on a spiritual concept: Being born into the Kingdom of God.
“But when the kindness and the love of God our Savior toward man appeared, not by works of righteousness which we have done, but according to His mercy, He saved us, through the washing of regeneration and renewing of the Holy Spirit” (Titus 3:4-5).
That purification of spirit and new birth happens when we obey the truth of the Gospel (1 Peter 1:22-23). There is no way around it. If we hope to have a home in Heaven, then we must be born again.
This new birth is a new beginning, marking a pivotal moment in life when your thoughts and behavior patterns are forever changed (Romans 6:1ff).