Its hard to understand that how could jealousy, hatred or sin could exist in a place called heaven ?
Its hard to believe that when this could exist on heaven its much much easier to appear on this sinful earth.
Remember, this sinful earth was once sinless. :-) Not a taint of selfishness or pride existed here. However, we give God the praise that inspite of the present situation here, one day, His kingdom will come and His will be done on earth as it is in heaven all the time.
Each time I stop to think about sin being in heaven, and how it led to the expulsion of good angels turning rebellious, I can't help but reflect more on God's love and forbearance. Remember that God hates sin so much that He refused to look at His Son who became sin for us on Calvary.
The truth lies in how we view sin. We know sin because we were born in it, and because we practise it. We experienced it. Back then angels didn't fully understand what sin was, because they simply didn't know about it. It was more potential than real. Lucifer was the first to attempt through selfishness to make it real when he challenged God's government. Not even Lucifer fully understood the implications of his rebellion, but God is not in the business of allowing any of His creatures to explore sin's concepts just so they can learn not to commit it again. My God is pro-active, and so should we. That is why God has laws to protect us from the selfishness of sin.
God knew sin from a theoretical point of view. He knew of its implications, and potential harm if cherished, and that is why He had to nip it in the bud. He could never tolerate it in heaven.
Sin is so bad that God had to get rid of it completely, or it would totally destroy the whole universe. How would you have done it?
And the fact that there was war in heaven goes to show more of God and His love for each of us. God did not destroy Satan yet, but only cast him out of heaven until sin and its results could be seen. The end of sin will only come when all of creation agrees that it needs to be eradicated totally. Everyone will bow and acknowledge that their Creator is all wise and all loving.