Human life is a gift. However it develops later on, it starts as a gift. We say that a mother gives birth to a child. No one ever thinks of saying he gave himself life or birth. We all recognize that both were given to us. We did not work for or earn the life we have, nor did we even desire or will it. We came into the world for better or worse, without any say in the matter. We were just born. Whatever the known biological facts, it is God who gives the breath of life to every living soul.
Eternal spiritual life is as much a gift as natural life is. So Jesus Christ says, “You must be born again.” There is no alternative. How can a man believe he must be born naturally and yet not believe he must also be born spiritually?