I will give u understanding as God gave me understanding. When God created the angels He made them like the military but instead of rank He gave them power and authority. From the least in power and authority up to and including God's generals or archangels. Man and angel r made in the image of God, God is a spirit being, we and angels r spirit beings trapped inside a body.The difference between man and angel, angels have a different body and they have power and authority which man has no power and a little authority. We have a spiritual heart that is the center of our being and is where emotions and desires dwell in us and is where the inborn nature or God's Spirit dwells in us. The spiritual heart is located in the lower left side of our chest. The angels rebelled because they WANTED what God would not allow and they WANTED it MORE than they WANTED God. IF they would have WANTED God MOST then they would not have rebelled. We r here because of what they did. We r here to be tested and tried, molded and made ready for heaven. If we can serve god no matter the cost like Job and Joseph (Go through the fire). If we can surrender our will and do God's will for our life (Take up our cross). If we can say no to self, sin and the world here while being tempted (Overcome). If we can do all this here then when in heaven we will have no problem serving and obeying God. God will not just zap us and make us to where we will never rebel nor sin against Him. If He were to do this He would be programming us and we would be no more than robots and no longer free willed. When God cast Lucifer and his angels out of heaven Lucifer became the devil or satan and his angels became demons. God also took their bodies from them or they would be walking and mating with us as some once did. The inborn nature is nothing more than a demon (fallen angel) of the least power and authority. They cannot possess us as in demonic possession that requiress several with their combined power or one of a higher power, but they do controll us. They raise up emotions and desires, they give us urges, feeling and impressions, and they put thoughts in our head. If u will take note there is almost always a motive behind what we say, do and think. Do we say, do and think because of lust, greed, envy, jealousy, pride, anger, hatred etc. or do we say, do and think because of love, compassion, and long suffering etc. What is in our heart will come out in word, thought and or deed. When God's Spirit comes into our heart He cast out the inborn nature and also casts out bad emotions like greed, lust etc. because God will not dwell where sin dwells. When these bad emotions r no longer in our heart they no longer controll us it is how God makes it possible to say no to sin. The inbore nature is still with us but no longer in our heart and he will still raise up emotions, desires etc. to try to get us to sin. We can give into an emotion and allow it back into our heart and it will controll us til we repent and ask God to take it from our heart again. U say there is no tempter in heaven, that is correct but u will still WANT. WANT is why the angels rebelled. The bible says that we r tempted when we r drawn away because of our own lust. It is something that we WANT. U cannot be tempted by something that u truly care nothing about. We must do our part and God will do the rest. We must change ourselves with God's help. God uses these fallen angel to test and try, mold and make us ready for heaven. By overcoming and saying no to sin do we change. It helps us get to the place where we hate the things that cause us problems instead of WANTING them. God also gives these fallen angels what they WANTED but they must get it by expierencing what we expierence. Because of what Lucifer thought of himself (he was the most beautiful angel and he knew it) and because of what he WANTED he allowed pride to emter his heart. I hope this helps u.