The Holy Ghost, I have said dwells in body and soul, as in a temple. Evil Spirits indeed have power to possess sinners, but his indwelling is far more perfect; for he is all-knowing and omnipresent, he is able to search into all our thoughts, and penetrate into every motive of the heart. Therefore, he pervades us ( if may be so said) as light pervades a building, or as sweet perfume the folds of some honourable robe; so that, in Scripture language, we are said to be in him, and he in us. It is plain that such an inhabitation brings the Christian into a state altogether new and marvelous, far above the possession of mere gifts, exalts him inconceivably in the scale of beings, and gives him a place and an office which he had not before. In Saint Peter’s forcible language, he becomes “partaker of the Divine Nature”, and has “power” or authority, as Saint John says, “to become the Son of God”. Or, to use the words of Saint Paul, “he is a new creation; old things are passed away, behold all things are become new”. [...]
This wonderful change from darkness to light, through the entrance of the Spirit into the soul, is called Regeneration, or the New Birth; a blessing which, before Christ’s coming, not even Prophets and righteous men possessed, but which is now conveyed to all men freely through the Sacrament of Baptism. By nature we are children of wrath;the heart is sold under sin, possessed by evil spirits; and inherits death as its eternal portion. But by the coming of the Holy Ghost, all guilt and pollution are burned away as by fire, the devil is driven forth, sin, original and actual, is forgiven, and the whole man is consecrated to God. And this is the reason why he is called “the earnest” of that Saviour who died for us, and will one day give us the fullness of his own presence in heaven. Hence, too, the is our “seal unto the day of redemption”; for as the potter moulds the clay, so he impresses the Divine image on us members of the household of God. And his work may truly be called Regeneration; for though the original nature of the soul is not destroyed, yet its past transgressions are pardoned once and for ever, and its source of evil staunched and gradually dried up by the pervading health and purity which has set up its abode in it.
Blessed John Henry Newman +1890