We are to learn from this report of the casting out of a devil the most consoling truth that Christ is the Lord over the devil and his realm; and, further, that this work, then begun in the body, did not terminate, but still continues in the Church of Christ, and will continue until the judgment day. For the accomplishment of this work Christ has instituted the necessary means; namely, Holy Baptism, the Lord’s Supper, the Word and Absolution, also other offices pertaining to the ministry, whereby the devil is to be cast out from the people, so that they may become free from his thralldom and that his kingdom may be destroyed. For it is plainly written in this respect: Verbum meum non redibit vacuum – My Word shall not return void. As the rain which falls upon dry land produces vegetation and blossoms, thus does the Word of God, most assuredly, produce fruit in some hearts. The Holy Spirit is connected with the Word to illumine, incite and purify the hearts, that they may be set free from the tyranny and oppression of the devil. This transaction is not visible to the outward eyes, as it was when Christ cast out the devil; it may be entirely imperceptible to the world, which is indeed not worthy to see the least spark of divine light and power, and which is blind, reviles, abuses and defames that which is good, as it did even here in the presence of Christ. We, however, who have and believe the Word, ought to perceive and know this truth which is so full of comfort, that God has ordained among us the means whereby we can and must continually cast out devils.  (Luther’s House Postil, Sermon for Oculi, Volume 1, p. 272-273)