This thread wouldn't be complete without pointing out that the single largest organization of Christians in the world, the Roman Catholic Church, 100% accepts evolution, although they argue that the process was guided by God to the eventual result. Question should be "why are Protestants so threatened by evolution?"
Evangelical* Protestants. Flat out guarantee you that Mainline Protestants believe in evolution at a higher rate than Catholics.
Implying that "Evangelical" and "Mainline" are mutually exclusive...