Amazing this question was posted two years ago.

My answer is, a cult is a seperation from the orthodox belief system of any religious belief, example anything that is not Biblicial Christianity, that calls itself Christian would be called a cult. Anything that would not be Quran Islam, that calls itself Islam would be a cult. For a Christian to say Islam is a cult is not the correct use of the word, because Islam is not a schism of Christianity, they do not believe Jesus is the Son of God.

Samuel