When we connect to Jesus in love for Him. Believe that God can do the work in my life that needs doing. Not have faith towards the dead works that my flesh can do, but faith towards God. And since this entire opportunity to enjoy God's power in our lives comes from the beginning point of uniting with Jesus' death, we are said to abide in the vine Jesus. That is something that is alive.
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.