Teresa [of Avila] and John [of the Cross] maintain that God is closer to us than we are to our very selves. We are born in union with God and we "live and move and have our being" in God throughout our lives (Acts 17:28). In keeping with the root meaning of "nature" (natura, "birth"), this union with the Divine is our human nature. It is so central to our being that John says that we could not exist without it. . . .
To quote John directly, "To understand this union of which we speak, know that God is present in substance in each soul, even that of the greatest sinner in the world. And this kind of union with God always exists, in all creatures."
— Gerald G. May, The Dark Night of the Soul