The Gospel of Jesus Christ is that by faith in Him as the One who died for our sins and rose again (I Corinthians 15:1-8), we are born into the family of God, whose heritage is eternal life.
This raises the question of what the central issue is to the new birth experience. I have had, over my lifetime, a fair amount of exposure to people's opinions about this central issue. When I go to funerals in certain traditions, I hear that being born again is what happens when a person is baptized. In a recent edition of the religion section of a certain newspaper, I read that our former governor said the central issue of the new birth experience is the yielding of our will to God. There is an enormous group of religious people who claim that a baby is born into its earthly family at physical birth (if it manages to escape the abortion clinic), and then is born again into God's heavenly family when its parents submit it to a certain religious ritual. Others say that we are born again when we do this or that other thing.
The question is: what does the Bible say?
This is the bottom line. The Bible is the Word of God and the visible churches are, at best, dim reflections of that Word. Many of them make the claim to divine sanction and authority; some of them actually claim that no one can be understanding the Bible aright unless they understand it according to their teaching; and a few even say that only their members will end up in heaven. But, despite the claims (which are only claims) the key question is still: what does the Bible say?
Well, consider 1 John 5:1: "Whosoever believeth that Jesus is the Christ is born of God...". As Paul said in 1 Corinthians 15, as Jesus said in John 3, so John writes in 1 John 5 that the central issue of the new birth is what we believe about Jesus Christ.
This automatically eliminates water baptism as the central issue because people can get baptized while believing most anything, but people can only be born again by believing in the specific Truth about Jesus Christ. This also eliminates the new birth of infants through religious ritual because infants don't believe anything about much of anything, and the Bible says pointedly that the new birth is through the faith of the one being born (not his/her parents). This also eliminates yielding our wills to God because that can only happen after we believe in His grace and goodness to us, so it is the fruit of the new birth, not the heart of it.
This also automatically eliminates faith in anything except Jesus Christ. If we believe in our church, we are not born again by that. If we believe in our current human religious leader, we are not born again by that. Constantly the Scriptures pull down all of the walls which we erect to keep from having to deal with God one on one. If we have been born by faith into His family, He is our Father. We have no need of walls to keep Him at a distance. But, if we have not been born again, we desperately need as many walls as we can get between us and Him.