Why do "Christian" hate groups like to burn the cross ?

I would think that burning a cross would be just as offensive as burning a flag. Why do these supposed “Christian” hate groups such as the KKK perform this practice. I know what it means now, but why was this image chosen in the first place.

My guess is that it is because Christianity is an important part of many black communities. Perhaps the hate groups think that a burning cross represents hell ? Does the fire have a different meaning in their minds - like burning a flag when it becomes worn ?

From a Supreme Court case (Capitol Square Review Bd. v. Pinette (94-780), 515 U.S. 753 (1995), http://supct.law.cornell.edu/supct/html/94-780.ZC.html ):

So, appearantly, it started out as a way to intimidate black people, but today the various KKK groups often try to pass it off as a “religious ceremony” symbolizing that “Christ is the light of the world”. Whether or not they really believe this themselves, or just want constitutional protection for harassing people they hate, I cannot say, but I lean towards the latter answer. Here is a page from a Texas nut group, the “Texas American Knights”:

http://www.texasamericanknights.org/cross.html

Why does the Ku Klux Klan burn crosses?

…and there it is. Thank you both for the especially informative posts.