Mormonism teaches that God used to be a man on another world and that we can become gods, but in order to achieve this, you must be an LDS member.

Does Mormonism attack other religions?  Yes it does.  The Book of Mormon says that all other religions are of the devil and complete abominations.

Let's compare Mormonism with traditional Christianity as revealed in the Bible. If Mormonism is Christian, then shouldn't it reflect biblical teachings?

Feelings are subjective and don't always reflect the truth.  What do Mormons use to determine spiritual truth?  They pray and subject God's word to their feelings.

Joseph Smith, the founder of Mormonism, said a lot of very "interesting" things about God being a man, the Trinity is three gods, temple work, and people on the moon...

Brigham Young, the 2nd Mormon Prophet, said that God is progressing knowledge, that to deny polygamy is to court damnation, and that God and Mary 'did it.'