This morning I got into a discussion about sin with a commenter at TitusOneNine. Here's an edited version of what I said.
As to 'sin,' certainly we're all sinners in that we all make 'bad choices.' But we understand very little about why and how we make any choices at all, bad or good.
Traditional Christian models of 'sin' don't offer us much insight here. And when it comes to the acid test, that of combating sin (let alone all but wiping it out as we have, say, polio), traditionalist sin models have an uneven track record, to put it politely.
Combating sin with prescriptions derived from traditionalist models is analogous to the way doctors used to treat peptic ulcers with diet changes and stress reduction. In the case of peptic ulcers, sometimes the treatment worked, sometimes it didn't. The trouble was, doctors could never reliably predict which it would be for a given patient. When the treatment did work, they didn't understand why, because they didn't understand how and why people got peptic ulcers in the first place.
It's much the same with the traditionalist 'treatment' for sin. By this I mean the usual prescription of accepting Jesus into your heart, believing that he was God incarnate who died for our sins, and so on. Sometimes the treatment works, but very often it doesn't. We can't reliably predict which it will be for a given sinner. And when the treatment does work, we don't understand why, because we don't understand how and why people make the choices they do.
In the case of peptic ulcers, doctors eventually figured out that most common peptic ulcers are caused by a particular type of bacteria, Helicobacter pylori. The standard treatment is now an inexpensive course of antibiotics.
In the analogous case of sin, we've got a lot of work to do to reach that level of understanding. I would venture that many nonbelievers and doubters instinctively understand this, and for that reason (among others), exclusivist claims about Jesus strike them as foolish nonsense. This certainly doesn't help our efforts to bring such people to God.

Well said, D.C.
One problem you encountered on that site is the age-old one of idolatry: confusing symbol with referent.
Most Christians assume that because an eternal reality they label "Christ" is revealed by Jesus' life and teaching that Jesus and Christ are strictly identical. That is a huge mistake.
Posted by: David | January 08, 2007 at 07:06 PM
I don't think I quite understand your analogy.
I'm not sure how you can say that in some cases the treatment for sin doesn't work. Have you been to hell and personally seen Christians who thought they were saved through Jesus Christ and it turns out they weren't ? Or do you mean that Christians continue to sin after they come to Christ, as if becoming a Christian, or confessing their sins (not sure what "treatment" you speak of) should yield as a result a sin-free life afterwards ?
If you are looking for a perfect life here on earth, no, Christianity is not the "treatment" you should follow. I don't know that there is a prescription that claims such an outcome - well. maybe the MDGs ;) Seriously, our hope as Christians is that we will be perfectly happy and at peace and in perfect communion with God in everlasting life, not in this one. Which doesn't mean that our life will not be fuller and more at peace by the knowledge of our Savior, but that perfection will only be attained in the afterlife.
Posted by: Veronique | January 12, 2007 at 02:31 PM
Veronique, visiting from TitusOneNine, writes: "Or do you mean that Christians continue to sin after they come to Christ, as if becoming a Christian, or confessing their sins (not sure what "treatment" you speak of) should yield as a result a sin-free life afterwards ?"
Maybe not a sin-free life, but certainly a less-sinful one. (Welcome, BTW.)
Posted by: D. C. | January 12, 2007 at 05:05 PM