What was the purpose of Lucifer’s creation?

Lucifer was originally created by God as a cherub that covered the throne of God (Ezekiel 28:14).  Some even say that he was sort of the song leader in Heaven because of the great gift of his voice (Ezekiel 28:13).  However, at some point in time after God finished creation, Lucifer became prideful in his beauty and decided that he wanted to become like the Most High (Ezekiel 28:16; Isaiah 14:12-14).  While this was his original job, it may not have been his created purpose.  In order for God to allow free will there has to a choice of whether or not to follow Him.  There also has to be a second choice, otherwise there is no choice to be made.  Satan’s purpose is to give mankind the choice to love and follow God.  If we don’t choose God, we choose Satan.