I have often wondered why the First Epistle of John (one of my favorite books of the Bible) ends with the above emphatic command, which seems almost out of place to the themes of the body of the letter (living right, loving one another and believing the right things about Jesus). David Powlison has a good answer:
.....John’s last line properly leaves us with that most basic question which God continually poses to each human heart.
Has something or someone besides Jesus the Christ taken title to your heart’s trust, preoccupation, loyalty, service, fear and delight?
It is a question bearing on the immediate motivation for one’s behavior, thoughts, and feelings. In the Bible’s conceptualization, the motivation question is the lordship question.
Who or what “rules” my behavior, the Lord or a substitute?
The undesirable answers to this question—answers which inform our understanding of the “idolatry” we are to avoid—are most graphically presented in 1 John 2:15-17, 3:7-10, 4:1-6, and 5:19. It is striking how these verses portray a confluence of the “sociological,” the “psychological,” and the “demonological” perspectives on idolatrous motivation.
The inwardness of motivation is captured by the inordinate and proud “desires of the flesh” (1 John 2:16), our inertial self-centeredness, the wants, hopes, fears, expectations, “needs” that crowd our hearts.
The externality of motivation is captured by “the world” (1 John 2:15-17,4:1-6), all that invites, models, reinforces, and conditions us into such inertia, teaching us lies.
The “demonological” dimension of motivation is the Devil’s behavior-determining lordship (1 John 3:7-10,5:19), standing as a ruler over his kingdom of flesh and world.
In contrast, to “keep yourself from idols” is to live with a whole heart of faith in Jesus. It is to be controlled by all that lies behind the address “Beloved children” (see especially 1 John 3:1-3,4:7-5:12). The alternative to Jesus, the swarm of alternatives, whether approached through the lens of flesh, world, or the Evil One, is idolatry.
Hat Tip: Justin Taylor