In this episode of Religion Today, host Martin Tanner describes how traditional Christianity believes there was a time in the beginning when God alone existed.  Nothing else, not space, matter, energy or life existed.  God created everything ex nihilo out of nothing.  In LDS theology, not just God, but all matter, energy and life, in the form of intelligence or spirit, has always existed.  Joseph Smith explained, as recorded in D&C 93:33 "[T]here is no immaterial matter."  Anything that is created can be destroyed.  Ultimately, LDS theology would say God, through eternal progression, moved from being like humans are now, through progression, into the being he is now.  In that sense, God through progression turned himself into God.