Okay, quick spelling test. Spell "sin". Oh, you peeked! Notice the letter at the middle of the word. As it turns out, "I" at the middle of "sin" is actually somewhat of a reasonable explanation of the word.
Turns out that we are not the center of the universe. I know, that may come as a shock to some. We read at the beginning of everything, "In the beginning, God created the heavens and the earth." (Gen 1:1) Not you. Not me. God. As Creator, He qualifies as the Center of the Universe. We, however, are quite happy to steal that title for ourselves. We are perfectly satisfied, even as Christians, offering the oxymoronic "No, Lord" to God. Because above all else what we want and think and feel are the highest priority for us. God says, "Thou shalt ..." and "Thou shalt not ..." and we'll evaluate His command, determine whether or not it suits us, and then decide if we'll go along with Him. Some of us do it self-consciously. Others do it unconsciously. All of us do it at one time or another.
The problem, you see, is not the devil. Oh, he is a problem. He and his sort cause all sorts of difficulties. But, like the saying goes, "Lead me not into temptation; I can find it on my own." Or, in biblical terms, "Each person is tempted when he is lured and enticed by his own desire. Then desire when it has conceived gives birth to sin, and sin when it is fully grown brings forth death." (James 1:14-15) James lays the blame for our sin at our feet. Because "sin" has an "I" at the very middle.
This is why the Bible doesn't talk about reforming people. It talks about transforming people (Rom 12:2). It doesn't talk about reparative therapy; it talks about death to self (Rom 6:7-8; Col 3:3; 2 Tim 2:11). We aren't looking for a "better you"; we need sanctification (1 Cor 6:9-11; Heb 10:10,14). He isn't planning to repair the old; He will make something new.
Because at the center of sin is "I". And that "I" is the problem.