True to form, Al Mohler has given his T4G talk a provocative title: "Why Do They Hate It So? The Doctrine of Substitution." Today's question for a free 08 conference registration is

Why do you think the doctrine of substitution, as Al Mohler's talk puts it, is hated so?

Contest rules:

1. Post your answer in the "comments" section.
2. Your answer must be accompanied with a working email address.
3. Each question will remain open for 24 hours.