What you choose to attribute ultimate worth to—what you choose to worship—depends on what you fear the most. If you fear loneliness, you worship relationships. You depend on them to save you from a meaningless life. If you fear not being accepted or esteemed, you worship your social network, the way you look, the car you drive, or the amount of money you make. You depend on these things to validate your existence. If you fear insignificance, you end up worshiping your career or your accomplishments.
Behind everything you worship is some fear that, without this person or thing, you’d be lost. We’re all worshipers—but God is the only reliable object of worship because nothing and no one extends these things like God does in the person and work of Jesus Christ.
According to the Bible, anything we worship—other than God himself—is an idol. Idolatry is centering our attention and affection on something, or someone, smaller than God. In fact, most idols are good things in our lives that we turn into ultimate things, things that take God’s place as we unconsciously depend on them to give our lives meaning and security.
Idolatry is trying to build our identity around something besides God. And this is not just a problem for non-Christians; it’s a problem for Christians too. Christians also are guilty of trusting in things smaller than God to give their lives meaning and significance. So, let’s not make the mistake (like Jonah does here) of thinking that idolatry is only a non-Christian problem.
~Tullian Tchividjian, Surprised By Grace (pp 120-121).