Sins (fruit of iniquity) exists within the soul because of our past choices join ourselves to Sin (the kingdom of darkness). The joining produced offspring which does not reflect the image and likeness of God. He calls this iniquity. Through grace and truth, we learn to use tokens provided by God for us to separate ourselves from Sin (the kingdom) and through our learned function as priests, we experience the work of Christ purging sins (the fruit of that kingdom) from our hearts... this is know as the work of regeneration or the operation of God.
Learn how you too can experience this "Common Salvation" taught by His apostles: http://www.s8wministries.org/general.php?id=35