For although they knew God, they did not honor Him as God or give thanks to Him, but they became futile in their thinking, and their foolish hearts were darkened. Claiming to be wise, they became fools, and exchanged the glory of the immortal God for images resembling mortal man and birds and animals and reptiles. Therefore God gave them up in the lusts of their hearts. . . . For this reason God gave them up to dishonorable passions. . . . And since they did not see fit to acknowledge God, God gave them up to a debased mind to do what ought not to be done.--Romans 1: 21-24a, 26a, 28 (ESV, emphasis added)
Sin is not the natural condition of man. God made mankind in His image and pronounced a judgment that man was "good."
Yet Adam and Eve chose not to "honor Him as God" and obeyed their own desires. That is the root of idolatry: not acknowledging God.
We all do the same thing. Though creation shows us God's hand, we close our eyes. When the sound of the waves pounds our ears, we shout "la la la la la" to drown it out. Then, we choose our idol and make that our god.
And God does not leave such idolatry unpunished.
Instead, He gives us over to more and more sin. Each sin that tempts us can in some respects be traced back to idolatry, the root sin of our flesh.
Non-Christians: the things you do and then later regret are not isolated flare-ups of some alien force exerting control over your body. Those sins are just the first step in God's eternal punishment. Don't let another day go buy without acknowledging Jesus as Lord and turning to Him.
Christians: have you gotten to the root of your sin? I still struggle with sin, and I'm beginning to suspect that I simply treat the symptoms without curing the disease. Let's strive to destroy our root sin of idolatry and then move on to the branches of sin.