Mormons believe Jesus Christ is the Son of God who died and rose again for our sins. Many who call them a cult because they don't believe all the Bible, are also guilty of not believing in all the Bible - that's the deal with all religion; it is man-made and sinful. They have what I consider some outre' beliefs, but then again, so do all the religions I have been exposed to - some human decided that certain parts of the Bible don't fit their sensibilities so they modify, adapt, and bastardize the parts they don't like - quite often to make their priests look like something special.
While folks of a number of religions look down on Mormons as non-Christian, there is one Church that thumbs its nose at all the Christian religions that aren't it because they think they are the elite - they also elevate their clergy to something super-human and holy instead of admitting that they are still mere human mortals and therefore not a whit better than the lowest of humans.
Demons in hell believe the same thing about Jesus. (And no, I’m not calling LDS folks demons, but rather making a point).
Mormons also believe Jesus and Satan are brothers; they deny that salvation took place on the Cross. One must believe basic Christian doctrine to BE a Christian; Mormons deny it and add their own.
Then throw in their teachings about having your own planet when you die, and the blasphemous mess about God once being human and physically impregnating Mary. Mormonism is simply not Christian, no matter how you wish to spin it or excuse it.