Nothing is so powerfully effective against the devil, the world, the flesh, and all evil thoughts as to occupy one’s self with God’s word, to speak about it and meditate42 on it, in the way that Psalm 1[:2] calls those blessed who “meditate on God’s law day and night.” Without doubt, you will offer up no more powerful incense or savor against the devil than to occupy yourself with God’s commandments and words and to speak, sing, or think about them. Indeed, this is the true holy water and sign that scares the devil to run away.43
42 Luther’s word translates as “thinking,” without necessarily implying a methodological contemplative prayer-reflection used in monastic life or specific spiritual practices. Here Luther presents an invitation for the ordinary Christian to learn a habit of prayer and in faith engage the word as the compass in one’s life.
43 In Luther’s medieval world, it was common to use “holy water,” das rechte Weihwasser (Ger.), aqua illa sancificat (Lat.), or “sanctified water/water that sanctifies” in, e.g., exorcisms to drive away evil spirits.
Kirsi I. Stjerna, “The Large Catechism of Dr. Martin Luther,” in Word and Faith, ed. Hans J. Hillerbrand, Kirsi I. Stjerna, and Timothy J. Wengert, vol. 2, The Annotated Luther (Minneapolis, MN: Fortress Press, 2015), 292.