Mormonism (The Church of Jesus Christ of Latter-day Saints) - Is it Christian? (page 3)
Mormonism says: All human beings and spirits, including Jesus and Satan, existed as spirit beings before being born. Physical birth gives bodies to these spirits, and an opportunity to choose right or wrong. Thus the present life is a period of probation. The way a person lives in this life determines their status in the life after the resurrection. If the deeds of this life have been satisfactory and all temple obligations have been fulfilled, the individual becomes a god and is considered eligible to create “spirit children” as God the Father did and populate a world of his own.
The Bible says: There is no pre-existence of human spirits in an earlier life before our Earthly existence; the Bible does not teach this in any form. And humanity is permanently on a lower level than God. Though we may become like Him in moral purity in heaven, we never become infinite in regard to time, space or ability. And the Bible says nothing about populating other worlds—simply about the future kingdom of Christ and the New Jerusalem on this world (Revelation 21-22).