If sin made sense, it wouldn't be sin.

Douglas Wilson writes,

But people act the way they do because of sin. And if sin made sense, it wouldn't be sin. This is the mystery of lawlessness. A man can engage in behavior that is self-destructive, knowing full well that it is self-destructive, and do it anyway, with his eyes wide open. Wisdom says in Proverbs that all who hate her love death (Prov. 8:36). When you are trying to set the paths of life before a man who loves death, and you are assuming that he is doing what he does because he actually doesn't love death, this is going to result in a very clear, cogent, and impotent teacher. The law can't save.

Read the whole thing if you want, but this paragraph was really all I wanted to post on. In other words, Wilson's original post is well worth reading, but my point is to acknowledge the irrationality of sin, namely that "A man can engage in behavior that is self-destructive, knowing full well that it is self-destructive, and do it anyway, with his eyes wide open."

I know this from first-hand experience, and I expect, with a little honesty, that you do too. So, what is the solution? The gospel, of course. The teacher, whoever that might be, must be able to preach a good-ol' come to Jesus sermon—to the dead.