Thomas Chalmers was a Scottish pastor and professor in the first half of the nineteenth century. "The Expulsive Power of a New Affection" is a sermon preached during his many years of ministry. Here are some comments to help explain it. You can read it here:
https://www.monergism.com/thethreshold/sdg/Chalmers,%20Thomas%20-%20The%20Exlpulsive%20Power%20of%20a%20New%20Af.pdf
“Love not the world, neither the things that are in the world. If any man love the world, the
love of the Father is not in him.” - 1 John ii. 15.
This is the Scripture passage for his sermon.
"THERE are two ways in which a practical moralist may attempt to displace..."
He argues that human nature is not able to simply stop loving of the world, but it must be replaced a greater love, namely, the love of God. Only a new affection for God has the power to expel an old affection for the world.
"The misery of such a condition is often realized by him who is retired from business"
He gives many examples of how a person cannot simply stop a pursuit. It would leave him empty and miserable. Instead, a person will always replace a former pursuit with some other pursuit.
"It is this which stamps an impotency on all moral and pathetic declamation about the
insignificance of the world."
It's pointless to reason with people about the evils of worldliness in order to make them change. You may be right, but no one will actually give up their worldliness until you show them something more attractive to pursue.
"Its desire for one particular object may be conquered; but as to its desire for having
some one object or other, this is unconquerable."
You may give up your desire for money, but only by replacing it with a desire for power. The object of the desire may change, but the desire itself remains constant.
"To bid a man into whom there has not yet
entered the great and ascendant influence of the principle of regeneration, to bid him
withdraw his love from all the things that are in the world, is to bid him give up all the
affections that are in his heart."
He applies this insight into human nature to effective preaching of the Gospel. Don't try to convince people to live godly lives if they don't yet know God.
"The arithmetic of your short-lived days, may on Sabbath make the clearest
impression upon your understanding - and from his fancied bed of death, may the preacher
cause a voice to descend in rebuke and mockery on all the pursuits of earthliness..."
On Sunday morning, you may feel swayed by the preacher...
"But the morrow comes, and the business of the world, and the objects of the world, and the
moving forces of the world come along with it - and the machinery of the heart, in virtue of
which it must have something to grasp, or something to adhere to, brings it under a kind of
moral necessity to be actuated just as before"
But the necessities of Monday will come and drive out that feeling very quickly.
"Beside the world, it places before the eye of the mind Him who made
the world and with this peculiarity, which is all its own - that in the Gospel do we so behold
God, as that we may love God."
God is more attractive than the world because God made the world and through the gospel we can behold and love Him.
"Thus may we come to perceive what it is that makes the most effective kind of preaching."
He is arguing against the moralists who preach obedience to God's law and not the love and knowledge of God himself.
"Let him be but a faithful
expounder of the gospel testimony unable as he may be to apply a descriptive hand to the
character of the present world, let him but report with accuracy the matter which
revelation has brought to him from a distant world - unskilled as he is in the work of so
anatomizing the heart"
A good preacher tells the good news accurately, even if he isn't a skilled psychologist or insightful cultural analyst.
"No wonder that they feel the work of the New
Testament to be beyond their strength, so long as they hold the words of the New
Testament to be beneath their attention"
The moral demands of the Bible are impossible to those who disregard the person and work of Christ in the Bible. We love Him because He first loved us.
"The man who believes in the peculiar doctrines, will readily
bow to the peculiar demands of Christianity. When he is told to love God supremely, this
may startle another; but it will not startle him to whom God has been revealed in peace,
and in pardon, and in all the freeness of an offered reconciliation."
But the opposite is also true. Those who believe the Gospel see the moral demands of the Bible as being right and good.
"Separate the demand from the doctrine; and you have either a system of
righteousness that is impracticable, or a barren orthodoxy. Bring the demand and the
doctrine together - and the true disciple of Christ is able to do the one, through the other
strengthening him."
The demand of Christian obedience can only come after the doctrine of Christian salvation.
"Thus it is, that the freer the Gospel, the more sanctifying is the Gospel; and the more it is
received as a doctrine of grace, the more will it be felt as a doctrine according to godliness.
This is one of the secrets of the Christian life, that the more a man holds of God as a
pensioner, the greater is the payment of service that he renders back again."
If the gospel is preached as a gift of grace, received only by faith, it moves us more to godly living. If we mix in some obligation of works, it corrupts our motivation and does not lead to greater godliness.