Satan was cast down from heaven because he rebelled against God. This happened long before he created man.
Revelation 12:4-5And there appeared another wonder in heaven; and behold a great red dragon, having seven heads and ten horns, and seven crowns upon his heads. And his tail drew the third part of the stars of heaven, and did cast them to the earth: and the dragon stood before the woman which was ready to be delivered, for to devour her child as soon as it was born.However, the best description of what happened comes in Ezekiel 28. Here Satan is given the title king of Tyrus. A lot of people seemingly want to argue that the king here is a man as the price before him, but they ignore what God tells them:
Ezekiel 12:12-14Son of man, take up a lamentation upon the king of Tyrus, and say unto him, Thus saith the Lord GOD; Thou sealest up the sum, full of wisdom, and perfect in beauty.
Thou hast been in Eden the garden of God; every precious stone was thy covering, the sardius, topaz, and the diamond, the beryl, the onyx, and the jasper, the sapphire, the emerald, and the carbuncle, and gold: the workmanship of thy tabrets and of thy pipes was prepared in thee in the day that thou wast created.
Thou art the anointed cherub that covereth; and I have set thee so: thou wast upon the holy mountain of God; thou hast walked up and down in the midst of the stones of fire.I've made a break here for a reason.
Ezekiel 28:15-17Thou wast perfect in thy ways from the day that thou wast created, till iniquity was found in thee. By the multitude of thy merchandise they have filled the midst of thee with violence, and thou hast sinned: therefore I will cast thee as profane out of the mountain of God: and I will destroy thee, O covering cherub, from the midst of the stones of fire.
Thine heart was lifted up because of thy beauty, thou hast corrupted thy wisdom by reason of thy brightness: I will cast thee to the ground, I will lay thee before kings, that they may behold thee.
also why would God Give satan rule over our plane or domain maybee to make our heaven greater.
God didn't really give him rule; at least in the sense that he won't have absolute control, though he will come close. As we have seen from the book of Job, he can only do what God allows and nothing more. The explanation for us being here and things being the way they are is a complicated subject, because it's basically the reason for life. I cover this in my
The Earth Ages Bible Study because it would be much too long here.In a nutshell, we're here to find out whos side we're on. Satan is already condemned and he's trying to drag as many with him as he can. Afterall, he originally drew 1/3 of the host of heaven.