Whether Christian or not, whether acquainted with Scripture or not, we know the conflict within us between the obvious good that we should and the obvious evil we should not. In typical form, we know the wrong we are to avoid and with glint in the eye and sinful joy of fallen heart, we go for the wrong anyway. In much the same way, we know the pure and righteous that we should but so often we simply cannot bring ourselves to do it -- much less desire it.
It has been said the sin, especially original since no one has to teach us how to sin, is the one doctrine no one needs the Scripture to prove. Open your newspaper, check out the headlines on Twitter, listen to the news on TV or radio. We cringe at the evils that come from those who seem so little different from us. We grow weary of the ever constant litany of terrible and shocking things that people do to others (especially those whom they supposedly love most dearly). But then we look into the mirror and we know the shameful thoughts of our hearts and the bitter words that should never have been spoken and the gleeful delight we have taken in our clever dance with darkness. Then on some level we understand.
I do not worry about those who wrestle with this conflict between the good we should and the evil we should not. But I do worry and fear for those in whom there is no conflict -- only the emptiness of a mind and heart adrift without anchor in conscience and the voice of God to act as a rudder to direct the person. As unsatisfying as it is to live within the tension of St. Paul, it is the creative tension in which God is at work. Perhaps that is what Scripture means when it says the heart has been hardened or God has given the sinner over to his unrighteousness -- there is no tension, no conscience to reign on our sin parade, and no voice of God directing us to know evil and to know good. Strange it is that the fruit of sin's rebellion in the Garden is the terrible knowledge that none of us wanted to know -- how we long to know only goodness, righteousness, and peace but instead we know their dark opposites.
It would be an awful place to end were it not for the full context of St. Paul's words. . .
 For I do not understand my own actions. For I do not do what I want, but I do the very thing I hate.  Now if I do what I do not want, I agree with the law, that it is good.  So now it is no longer I who do it, but sin that dwells within me.  For I know that nothing good dwells in me, that is, in my flesh. For I have the desire to do what is right, but not the ability to carry it out.  For I do not do the good I want, but the evil I do not want is what I keep on doing.  Now if I do what I do not want, it is no longer I who do it, but sin that dwells within me.
 So I find it to be a law that when I want to do right, evil lies close at hand.  For I delight in the law of God, in my inner being,  but I see in my members another law waging war against the law of my mind and making me captive to the law of sin that dwells in my members.  Wretched man that I am! Who will deliver me from this body of death?  Thanks be to God through Jesus Christ our Lord! So then, I myself serve the law of God with my mind, but with my flesh I serve the law of sin. Romans 7:15-25 ESV