Mormonism is a cult

Mormonism is definitely a cult. Mormons are not Christians.
What follows is a summary of some of their beliefs. These beliefs are in contradiction to the Bible.

1. Mormons believe God is not eternal, or even the only God, but one who  inhabited a planet in the star system Kolob. 
2. They believe they can be saved by obeying Mormon doctrine.
3. They believe that God had a god that elevated God to godhood and that they, too, can be elevated to godhood.
4. They believe they lived as full-grown adults (the Doctrine of Pre-existence) in a spirit world before they were born. In Pre-Existence, they had friends and family and relationships and knowledge. While there, they were presented with the Plan of Salvation, which included being given a choice to be born as humans with the prize at the end being godhood of their own planet. They didn't have to and some were content to stay in the spirit world where they were already in heaven instead of taking the plunge and getting a shot at being God.
5. They believe that when their spirits passed into existence, they also passed through a Veil of Forgetfulness where they forgot their previous spirit lives. Here, they recreate their pre-existent families as eternal families.
6. Jesus and Satan were brothers and God liked Jesus' plan best so Satan rebelled. Mormons don't believe in the sin nature, or 'original sin'.
7. Mormons believe the purpose of human existence is to become like God.
8. Mormons also believe it is ok to lie about their beliefs and affiliations to non-Mormons and to new Mormon recruits under the 'principle' of "milk before meat.". So they are free to deny the crazier parts, (God was a man, there are lots of Gods, including them, they take spirit wives to become goddesses, etc.) on the principle that until a Mormon has been sufficiently indoctrinated (brainwashed), they will recognize how crazy it sounds and maybe refuse to join or even quit and then spread the word.
9. Mormons believe that after they die, they move back to the spirit world.  Some of them are imprisoned for not believing the Mormon gospel while on earth. Those that never heard the Mormon Gospel will be visited by Mormon spirit missionaries.
10. Mormons believe that the dead can be saved after death if they are baptized by proxy by living Mormons.  Mormons in this spirit world can still sin:  "Those who are righteous in this life will still be righteous. Those who were unrighteous will still be unrighteous. We will have the same desires after we die as we had while on this earth" (Gospel Fundamentals, "Life after Death," pg 195.).
11. Resurrection is in several parts and only those that had a perfect knowledge of the divinity of Christ yet chose Satan will be damned. The rest will go through various stages of perfection while in the post-life spirit world.
12. If you miss your dog, don't worry. Fido, (as well as every other dog, cat, hamster, pigeon, aardvark and platypus) will ALSO be resurrected during the last of the seven different resurrections taught by the LDS (Latter Day Saints, i.e. Mormons).
13. The Mormon Plan of Salvation is in seven parts as well, with final stage, logically enough, called the Final Judgment. At Final Judgment, those finally judged go to one of three heavens, as befits their works, or to the Outer Darkness, which is Mormon hell.