Christians have long wrestled with the question of how people actually change; how do Christians exhibit Christ-like character in the world? Scottish pastor Thomas Chalmers (1780-1847) is one example of a believer who contemplated such questions. He presented his answer in a sermon entitled “The Expulsive Power of a New Affection.” Chalmers understands the heart, the “inner core” of a person, to love certain things. All sorts of sinful and destructive behaviors will emanate from a heart that loves the sinful world system (1 John 2:15).

How do you change what the heart loves? The moralist will try to point out all that’s wrong with the world and the bad consequences of engaging in evil behaviors. Such efforts, however, won’t work because the heart is not moved solely by fear and consequences. Instead, Chalmers argues that the best way to turn the heart away from evil habits, desires, and loves is to present it with something better to love, something more “alluring” (pg. 34). Chalmers admits that it is very difficult to destroy sinful desires outright but “what cannot be destroyed may be dispossessed” (pg. 35). If you can’t obliterate a desire, you can turn your heart’s attention to a new one.

Some may argue that all that needs to be done is remove a sinful temptation from your life, and you will change. Chalmers points out that this method of mere subtraction will be ineffective because the human heart seeks to latch on to anything, and “it must have something to lay hold of” (pg. 36). Getting rid of one evil desire may just open the door for a different evil desire. Human beings are lovers and desire-ers, and the heart will inevitably start desiring something in the absence of anything. Just as nature abhors a vacuum, so does the human heart (pg. 41). Therefore, it is not enough to show the insignificance of the world (pg. 44). Instead, you must show people a greater beauty. As Chalmers has so eloquently said, “The only way to dispossess [the heart] of an old affection is by the expulsive power of a new one” (pg. 49). 

What, then, is the new affection which drives out love for the world? It is the love of God as revealed in Christ (pg. 51). The way the love of God is shown to sinners is through effective preaching, which not only shows sinners their sin but, more importantly, magnifies Christ. However, some people do not believe in Christ because their unbelief blinds them to the beauty of Christ (pg. 60). Christians should still be bold in proclaiming Christ and keeping the gospel pure. In fact, Chalmers points out that the “freer the gospel, the more sanctifying the gospel” (pg. 65). In other words, the more God’s grace is emphasized in the gospel, the more powerful the message will be in releasing the heart from its sinful desires. The Law can only expose the heart for its sinful desires, but the gospel provides a new heart through faith in Christ. Therefore, the only way to keep our hearts free from the love of the world is to keep them in the love of God (pg. 68).