The recent remarks of Dallas-area pastor Robert Jeffress, senior pastor of First Baptist Church Dallas, have ignited widespread criticism--primarily because they were directed towards a prominent political candidate, Mitt Romney, who is a Mormon.
Jeffress labeled Mormonism a "cult," which is hardly new. In fact, not calling Mormonism a cult is what is relatively new. From it's inception in the 19th Century in New York State, until the 1980s, Mormons themselves were quick to point out that they are not part of Christianity and distanced themselves from the church. Around that time, however, the Mormons began an aggressive PR campaign to try to show common ground such as "family values" and so forth. We've all seen the slick TV ads that tell a heart warming story then ended with "brought to you by the Church of Jesus Christ of Latter Day Saints."
Quick survey of key doctrinal differences:
Classic Christianity: One God in three Persons: Father, Son, Spirit. No beginning or end. Never changes.
Mormonism: Many gods (you become the God of your own universe if you do things right in this life and that's how our God did it.)
Classic Christianity: Jesus is eternally God the Son, not created.
Mormonism: Jesus and Lucifer (Satan) are brothers
Mormonism adds it's own Scriptures supposedly found in Upstate NY by Joseph Smith.
Mormonism also has a host of what you might call "oddities" that reflect the views of it's founder, Joseph Smith. For example, Mormonism claims the American Indians are brown skinned because they refused to believe the Gospel.