Birth is the beginning of a life. And new birth is the beginning of a person who for the first times believes in the union with Jesus so much so that they do something about it. They believe that Jesus died as them, so they repent of their sins and thank God they can be free from hell because of their faith in Jesus. They believe they were buried with Him so they are baptized and buried in water. But life is more than just being born.
Life is more than just being changed into a baby.
Then is when we need to get the foundation underneath us. We need to progress in LIFE by maturing away from infanthood. Grow into mature relationship with Jesus Christ. It is immature to simply go to church. That is the beginning.