Blessed are those who hear the Word of God and keep it. These words sum up our Lord’s entire lesson. He teaches us by warning us as well as promising us a blessing. He begins by casting out a mute demon from a man. Then, against the slander that he is of the devil’s kingdom, he shows himself to be God who casts out the evil spirit with his own finger. This is the source of our blessing, namely, that Christ destroys the power of the devil by saving us from sin and every evil.
But while Jesus teaches us this wonderful gospel, there is also some urgency in what he says. He isn’t merely insisting that we know God’s Word and agree with it. He is certainly saying this much. But he is also admonishing us to guard his Word and keep watch that we do not fall into the grips of the evil one. As the Proverb says (4:13), “Take firm hold of instruction; do not let go. Guard her for she is your life.” And then it continues (4:14,16): “Do not enter the path of the wicked, and do not walk in the way of evil… for they do not sleep unless they have done evil, and their sleep is taken away unless they make someone fall.”
Jesus is teaching the same Proverb. Keep watch on God’s Word so that you do not give the opportunity to the devil and his minions! They don’t rest until they have found a soul to murder, whether by possessing the body or deceiving the mind. Those who listen to God’s Word, take warning from it, and rely on it for their blessing are those who, as the psalmist says (34:13), keep their mouths from evil and their lips from speaking deceit. Those who ignore our Lord’s warnings will not find the blessing in his instruction. They will shrug Luke’s account off as part of a collection of superstitious myths, proving themselves to be no different than those whose lying lips identified God’s free salvation in Christ as the devil’s work. But those who recognize the danger of their sin and the devil’s lies find blessing in Christ’s words. They find their Savior from sin and Satan’s attacks. Jesus died so that he might give you his gracious Word (2 Cor 5:19). So guard it! Because in the midst of death it is your life.