Jesus was very emphatic about our need to be born again. The reason? The soul on its own cannot enter heaven.
When Adam and Eve ate fruit from the tree they had been warned not to eat from, they died. God told them, were they to eat from the tree of the knowledge of good and evil, they would die.
God’s spirit died in them the moment they ate the fruit.
Consequently, they were sent out of the Garden of Eden. They began to age, deteriorate, and eventually they died.
A further consequence of their sin is that everyone subsequently born into the world no longer has the God element in them. They are body and soul with no spirit. When the body dies only the soul is left.
The soul cannot enter heaven so awaits the end. The Bible refers to this as a ‘second death’. This is a perpetual or everlasting death from which there is no escape or hope.
The person who is born again has God’s spirit reborn in them. The soul with the spirit can enter heaven. That’s why Jesus said you must be born again.
This can only happen through forgiveness of sin, and Jesus is the only one who can make this happen.
Jesus took our place, and so paid for our sin. He did this in order for mercy and grace to be released, allowing for salvation for the soul. This salvation, however, can only be received through faith in Jesus the Christ.