“Define “cult” that excludes any Christian religion.”
Just read the major books on cults.
The Catholic site Catholic Answers will also give some information on their labeling of Mormonism as not-Christian.
http://www.catholic.com/library/noncatholic_groups.asp
That doesn’t negate the fact that there are plenty of biblically illiterate Christians in Mormon congregations, just as there are biblically illiterate Christians in Hagee’s congregation.