When I was preparing yesterday’s blog entry, I kept thinking about a famous sermon by 19th-century Scottish preacher Thomas Chalmers. When I say the sermon is famous, I mean that it is reprinted even today in the books of great sermons. The sermon is called The Expulsive Power of a New Affection (pdf). Even though the language is outdated, the message itself retains enormous power. Chalmers writes at great length (the sermon is over 7000 words) about the utter inability of the human heart to change itself by moral reformation. We cannot by trying harder change who we are. There must be a new and better power introduced. The whole sermon can be summed up in this one sentence:
The best way of casting out an impure affection is to admit a pure one; and by the love of what is good, to expel the love of what is evil.
And the application is in this sentence:
We know of no other way by which to keep the love of the world out of our heart, than to keep in our hearts the love of God – and no other way by which to keep our hearts in the love of God, than building ourselves up on our most holy faith.
I think he is entirely right. Moral reformation never works. We may change our outward behavior—and that is hard enough. But to change the heart itself—to redirect its desires—that we cannot do without help from outside ourselves. And this is precisely what the gospel promises. An old poem says it this way:
"Do this and live,” the law demands,
But gives me neither feet nor hands.
A better word the gospel brings,
Bids me fly and gives me wings.
That’s the point I was driving at in my letter yesterday to the man sleeping with his lady friend. Until the heart is captured by some higher power, a higher calling, a fresh vision of God, there will be no motive for real change. But when the love of God fills us from within, then we experience new desires, and “the expulsive power of a new affection” becomes a reality for us.
And as I was writing that entry, I started singing a mostly-forgotten gospel song called I Am Resolved. Like the sermon, it was written for another generation, but it speaks enduring truth in its own way. The first stanza seems very powerful to me:
I am resolved no longer to linger,
Charmed by the world’s delights.
Things that are higher, things that are nobler,
These have allured my sight.
There is great truth in every verse and in the chorus, and this simple song, taken together with Chalmers’ sermon, reminds us that rule-keeping cannot change the heart. But when the heart is set on Christ, and when Christ is enthroned in the heart, then divine heart surgery takes place, and what the law could not do, the gospel does, and we are truly changed from the inside out.