Keller certainly didn't invent the idea that idolatry is at the root of all sorts of sin (see this really old and really excellent sermon [PDF]), but I think he's more responsible than any other living human for reintroducing the concept to contemporary sermons and our everyday conversations. This book doesn't chase every thread of idolatry, but it makes the point rather well that we all ought to do that in our own hearts, and it gives us a paradigm to use as we do.
Our contemporary society is not fundamentally different from these ancient ones. Each culture is dominated by its own set of idols. Each has its "priesthoods," its totems and rituals. Each one has its shrines—whether office towers, spas and gyms, studios, or stadiums—where sacrifices must be made in order to procure the blessings of the good life and ward off disaster. What are the gods of beauty, power, money, and achievement but these same things that have assumed mythic proportions in our individual lives and in our society? (xi-xii)