Disclaimer: In no way is this meant to sway, pardon, or invite you to Christianity. I do find many of the rules, explanations and teaching to derive from a logically sound notion that provides for a better community and it is the actions of fundamentalists that cause more harm than good. I will always believe in the spirit of a law and never in the letter of a law. Because there are no absolutes Marine! Haha.
Though it is far more fun to agree with you and watch people get frustrated, I think I may be able to provide a logical explanation that does not derive from faith. Nor will I bore you with the tedious logic 101 arguments.
Think of the most righteous, pure, innocent person you know, like your child. Though his existence gives you much joy, meaning, and purpose, he does not intellectually provide you answers. The knowledge you gain from him is from examining his experiences and it is your intellect that comes to the conclusions.
Now, lets take a person who was a little (or a tremendously) wild individual when he/she was younger. This person does not possess innocence any longer, but what he/she is able to do is relate to anyone. Through said actions he/she is able to possess an understanding to which those people who were more responsible cannot. This relation to both sides (good and evil) provide a broader sense of life, thus giving them a more well rounded view of existence.
Some religious people will not accept this, and it is often ridiculed due to it possibly encouraging people to act irresponsibly. We supposedly sin enough are our own, therefor it is ridiculous to encourage more sinful behavior. Yet, this is the synopsis of St. Augustine's argument as to why the followers of Christ in the early Church should listen to him.
Now if I could be so bold as to "justify the ways of God to Man" (Milton). A person that possesses the ability to speak to all of humanity, rather than just those that already believe, make for a far more effective advocate than some one who has no experience beyond that of a solely Christian one. If you need further proof as to why this is, look at the many irrational personal attacks that are meant to sway you, or at least attempt to admonish your reputation. Not as effective at winning you over to the cause as say St. Augustine who would take the time discuss shared experiences in order to provide ways to expose you to God's existence.
In any case, I thought the tone of your question above solicited a genuine response. That, and unlike your discussion on absolutes, this thread was definitely a theological one. So it should be said that faith based and Scripture based answers are relevant. Then again, I am sure it was on purpose so as to inflame the religionists. And I have no issue with that, so fire away!