An interesting insight from the sermon I heard at Pr. Roemke's church this weekend. Preaching on Christ's temptation, he said something like, "When the Devil uses God's Word for his purposes, Jesus answers with God's Word."
We have a hermeneutical principle here! Scripture interprets Scripture! But there's more...
The Devil certainly knows God's Word and uses, or rather, misuses it. One way in which he misuses it is to apply further Law to the penitent, driving him to further despair. Heaping accusations on the guilty, the shame-filled sinner - "Satan" means "Accuser", after all.
Luther experienced this keenly. He personalized his struggle with sin as a struggle with Satan himself. But Jesus stands ready with that other word - of Gospel. The antidote to the devil's barbs and darts of doubt. He speaks to us a different word - a word which puts all accusations away. He reminds us he's paid the price, and our sin is no more.
Does the Devil also misapply the Gospel? Surely so! To those secure in their sins, he gives a "Jesus loves you" pat on the back. What better deception than to bulwark the impenitence of a sinner than by using God's own word to do it!?
And like he tempts Jesus, "doesn't the Word promise, 'you will not strike your foot against a stone?", he also tempts us to believe - inappropriately - in the promises of God. "The threats of the Law don't apply to you, sinner. You will not die."
We understand the proper use of Law and Gospel: The Law for secure sinners. The Gospel for penitent sinners. But Satan, an expert in twisting the Word, must also be an expert in twisting Law and Gospel.