Repent means to turn away from sin. It means to recognize what we have done to displease God, and to simply walk away from it. To stop doing it. Sounds easy, right? Sure, until you try it. Before you know it, one tiny sin trickles its way back to your doorstep. One little temptation.
Yet Scripture tells us repentance is necessary for Salvation. Indeed, Jesus takes sin so seriously He recommends doing whatever it takes to cut it out of your life.
If your right eye causes you to sin, pluck it out and cast it from you; for it is more profitable for you that one of your members perish, than for your whole body to be cast into hell. And if your right hand causes you to sin, cut it off and cast it from you; for it is more profitable for you that one of your members perish, than for your whole body to be cast into hell. (Matthew 5:29-30)
Not only does this passage tell you how serious Sin really is, and how serious God really is about it, but it tells you how impossible it is to fight it on our own. Cut your hand off? Pluck out your eye? Does Jesus really mean these things?
Fortunately, repentance isn't merely a turning away. It is also -- perhaps even more -- a turning to. We take our eyes off our own worldly temptations and fix them instead on Christ. And it is in Christ that true repentance becomes possible.
So I find this law at work: Although I want to do good, evil is right there with me. For in my inner being I delight in God’s law; but I see another law at work in me, waging war against the law of my mind and making me a prisoner of the law of sin at work within me. What a wretched man I am! Who will rescue me from this body that is subject to death? Thanks be to God, who delivers me through Jesus Christ our Lord!
So then, I myself in my mind am a slave to God’s law, but in my sinful nature a slave to the law of sin. (Romans 7:21-25)
We can't turn away from sin on our own. But we can turn to Christ, and in Him have the strength to truly repent.