http://www.boston.com/news/globe/liv...sh_presidency/
More than 40% of Americans identify themselves as Evangelicals. Combine that with the Gallup poll where 85% of Americans stated they believe in God and I think you have a pretty good answer as to why there are so many anti-Christian feelings against Bush. It's that 15% who feel left out.
For those who question Bush's Christianity it sounds like PBS will have a documentary which shows otherwise.