Mormons are definitely not Christians. It's not even remotely the same religion.
Christianity is monotheistic. It's an outstanding characteristic the single most important characteristic from which all of the other theology flows. Christianity believes in the unmade God, the uncreated God who always was/is... the necessary being who confers being upon all creation.
Mormons are polytheistic they believe there are many, many gods, in fact, a God for every planet in the universe that has people on it and that gods are made by other gods in an infinite regress....
At nearly every single important point of theology between Christianity and Mormonism Mormonism breaks away completely and it's always regressive back towards something that Christianity evolved out of or better stated something that the semetic people's evolved out of towards monotheism.