Counterfeit Gods by Pastor Timothy Keller is a bracing and articulate look at how easily the human heart worships the wrong things. In fact, he calls the heart a mass producing "idol factory." According to Keller, anything can serve as a counterfeit god, especially the very best things in life (job, family, etc.) His definition of an idol is when a "good thing becomes a supreme thing."
One of his best examples is human love. Since God has been removed from our culture, the highest good is now "apocalyptic romance." We look to sex and romance to give us the transcendence and sense of meaning we used to get from our faith in God. (p. 28)
He gives a powerful example from the Old Testament story of Jacob and his wives. Jacob wanted Rachel more than anything and recklessly entered into an agreement with her father. He was tricked into marrying the wrong sister and doesn't know it till the next morning. Keller quotes Genesis 29:25: "And in the morning, behold, it was Leah!" He contends that all our idols are always imitations of the real thing, God himself. No matter what we put our hope in, in the morning it's always Leah, never Rachel. (p. 37)
After defining idolatry and explaining man's propensity to worship other gods, he gives guidelines for eradicating the false gods in our lives. Our primary action has to be to replace these idols with the only one who can satisfy our deepest needs and longings. Keller repeatedly emphasizes that idols cannot just be knocked down. They must be replaced. He argues that when we experience God's love in a profound way (i.e., when we know that God loves, cherishes and delights in us), we can rest our hearts in Him for significance and security. (p. 17)
The way to maintain an idol free life is to practice the spiritual disciplines as acts of worship. It is worship that is the final way to replace the idols of the heart. (p. 175)
For someone who has been steeped in biblical teaching, this might seem pretty basic, but for the unchurched (its target audience), Keller gives a solid explanation of why and how the human heart creates substitutes for God. These counterfeit gods cannot be simply removed. They must be replaced by the Lord himself.