Isaiah spoke of a war in heaven before our lives on earth. Satan fell and was cast out. This is the pre-mortal life we are talking about. Satan didn’t want to progress to become like God. He wanted to be God and supplant God. His pride caused his fall. The scriptures say he was “a son of the morning.” His name, Lucifer, means “light-bearer,” so he must have been intelligent and admired. One third of the host of heaven followed him and were cast out to the earth. They will never have bodies, and therefore will never have resurrection. Their purpose is to destroy or mislead those who desire to come unto Christ. They fully oppose God and therefore are evil. However, they also provide “opposition in all things,” which provides the opposite choices necessary for our agency — the right to choose good from evil.