One of the aspects of becoming a Christian is a new birth. Jesus spoke of this new birth to Nicodemus, who asked how a person can be born when he is old (John 3:4) in response to Jesus telling him that he must be born from above to see the Kingdom of God (John 3:3).
To understand what the new birth is and why it is necessary, we need to go back to the beginning. When Adam was created, He was made in the image (had a garment of light) and likeness (intelligent, rational) of God (Genesis 1:26). Even though as part of the original creation of humans God made us both male and female, He only created Adam. Therefore, Eve is not an individual creation; rather, she was built out from Adam’s side by God to be a helpmeet for him (Genesis 2:22), making it possible for the human race to propagate. Since we are all part of a single creation, Adam’s nature is passed on to his offspring. However, he did not pass on his original nature; rather, the nature his descendants receive was after he had corrupted it by trespassing and sinning (Genesis 5:3). This means that we all inherited his condemnation (Romans 5:12), and the spiritual and physical deaths that were a result of his trespass and sin (Romans 5:12-21). Physical death does not come upon us because of our personal sins, but as a direct result of Adam’s sin (Romans 5:14). Therefore, even if a human could live a completely righteous life before God, it would not be sufficient to save that one because the head of our creation is corrupt, condemned, and separated from God and therefore all his offspring […]