Before we came to this earth, we all existed in the presence of God as his spirit children.
Hebrews 12:9
9 Furthermore we have had fathers of our flesh which corrected us, and we gave them reverence: shall we not much rather be in subjection unto the Father of spirits, and live?
While we existed as spirits, we also had free will. Lucifer, who was in the presents of God, rebelled against God and created a war in heaven.
Revelation 12:7-11
7 And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels,
8 And prevailed not; neither was their place found any more in heaven.
9 And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.
10 And I heard a loud voice saying in heaven, Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ: for the accuser of our brethren is cast down, which accused them before our God day and night.
11 And they overcame him by the blood of the Lamb, and by the word of their testimony; and they loved not their lives unto the death.
In heaven, Lucifer was known as a son of the morning before he rebelled. His spirit was created in the image of God's spirit which is in the image of a man. For this reason the prophet Isaiah calls him a man.
Isaiah 14:12-17
12 How art thou fallen from heaven, O Lucifer, son of the morning! how art thou cut down to the ground, which didst weaken the nations!
13 For thou hast said in thine heart, I will ascend into heaven, I will exalt my throne above the stars of God: I will sit also upon the mount of the congregation, in the sides of the north:
14 I will ascend above the heights of the clouds; I will be like the most High.
15 Yet thou shalt be brought down to hell, to the sides of the pit.
16 They that see thee shall narrowly look upon thee, and consider thee, saying, Is this the man that made the earth to tremble, that did shake kingdoms;
17 That made the world as a wilderness, and destroyed the cities thereof; that opened not the house of his prisoners?
Lucifer, later named Satan was cast out of heaven for rebelling against his Father. He tried to get as many of us to follow after him as he could. He was very successful and managed to get one third of all the hosts of heaven to follow after him.
Revelation 12:4
4 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.
God's plan for his children was for them to become like him. But Satan had a different plan.
John 17:21-23
21 That they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us: that the world may believe that thou hast sent me.
22 And the glory which thou gavest me I have given them; that they may be one, even as we are one:
23 I in them, and thou in me, that they may be made perfect in one; and that the world may know that thou hast sent me, and hast loved them, as thou hast loved me.
1 John 3:2
2 Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when he shall appear, we shall be like him; for we shall see him as he is.
You see, God is a being of free will. Nobody tells God what to do. He does all the good things that he does of his own free will and choice. You cannot become like God unless you learn to choose good of your own free will and choice. God wants us to do good in and of ourselves. For this reason we are here to learn to overcome evil of our own volition. He knows that we will make some mistakes and need forgiveness. For this reason he provided a Savior that we might repent and continue trying to overcome evil and become like him.
Matthew 5:48
48 Be ye therefore perfect, even as your Father which is in heaven is perfect.
But in the pre-mortal existence, Satan came up with another plan. His plan was to force all of God's children to be good. He was very proud of his plan and wanted to be exalted above God for coming up with it. He was proposing a plan that He thought would save all mankind and not one soul would be lost. But God knew that mankind could not become like him with free will. God is a being of free will and unless mankind learns through their own free will to choose good over evil, they could never become like him. He therefore rejected Satan's plan. Satan was wroth and sought to turn away as many of the sons of God as he could and overthrow God's plan. For this reason God cast Satan out of heaven into this earth and all those who followed after him and rebelled against their Father.
Moses 4:1-4
1 And I, the Lord God, spake unto Moses, saying: That Satan, whom thou hast commanded in the name of mine Only Begotten, is the same which was from the beginning, and he came before me, saying—Behold, here am I, send me, I will be thy son, and I will redeem all mankind, that one soul shall not be lost, and surely I will do it; wherefore give me thine honor.
2 But, behold, my Beloved Son, which was my Beloved and Chosen from the beginning, said unto me—Father, thy will be done, and the glory be thine forever.
3 Wherefore, because that Satan rebelled against me, and sought to destroy the agency of man, which I, the Lord God, had given him, and also, that I should give unto him mine own power; by the power of mine Only Begotten, I caused that he should be cast down;
4 And he became Satan, yea, even the devil, the father of all lies, to deceive and to blind men, and to lead them captive at his will, even as many as would not hearken unto my voice.
Abraham 3:22-28
22 Now the Lord had shown unto me, Abraham, the intelligences that were organized before the world was; and among all these there were many of the noble and great ones;
23 And God saw these souls that they were good, and he stood in the midst of them, and he said: These I will make my rulers; for he stood among those that were spirits, and he saw that they were good; and he said unto me: Abraham, thou art one of them; thou wast chosen before thou wast born.
24 And there stood one among them that was like unto God, and he said unto those who were with him: We will go down, for there is space there, and we will take of these materials, and we will make an earth whereon these may dwell;
25 And we will prove them herewith, to see if they will do all things whatsoever the Lord their God shall command them;
26 And they who keep their first estate shall be added upon; and they who keep not their first estate shall not have glory in the same kingdom with those who keep their first estate; and they who keep their second estate shall have glory added upon their heads for ever and ever.
27 And the Lord said: Whom shall I send? And one answered like unto the Son of Man: Here am I, send me. And another answered and said: Here am I, send me. And the Lord said: I will send the first.
28 And the second was angry, and kept not his first estate; and, at that day, many followed after him.
We live in the last days before our Savior will come again on the earth and establish his kingdom and righteousness will reign upon the earth. Satan knows that he only has a short time before his time is up for 1000 years. This 1000 year period is known as the Mellennium. Satan and his angels, who were cast out of heaven into this earth, are here as disembodied spirits. They were not allowed to gain a body. For this reason they try to possess the bodies of those who were faithful in the pre-mortal existence as sons of God.
Mark 5:1-13
1 And they came over unto the other side of the sea, into the country of the Gadarenes.
2 And when he was come out of the ship, immediately there met him out of the tombs a man with an unclean spirit,
3 Who had his dwelling among the tombs; and no man could bind him, no, not with chains:
4 Because that he had been often bound with fetters and chains, and the chains had been plucked asunder by him, and the fetters broken in pieces: neither could any man tame him.
5 And always, night and day, he was in the mountains, and in the tombs, crying, and cutting himself with stones.
6 But when he saw Jesus afar off, he ran and worshipped him,
7 And cried with a loud voice, and said, What have I to do with thee, Jesus, thou Son of the most high God? I adjure thee by God, that thou torment me not.
8 For he said unto him, Come out of the man, thou unclean spirit.
9 And he asked him, What is thy name? And he answered, saying, My name is Legion: for we are many.
10 And he besought him much that he would not send them away out of the country.
11 Now there was there nigh unto the mountains a great herd of swine feeding.
12 And all the devils besought him, saying, Send us into the swine, that we may enter into them.
13 And forthwith Jesus gave them leave. And the unclean spirits went out, and entered into the swine: and the herd ran violently down a steep place into the sea, (they were about two thousand

and were choked in the sea.
Satan's time is running out. He will try to turn as many as he can away from God before he is bound for the 1000 years. For this reason you are seeing evil increase in the world. Be true to God and keep his commandments. The faithful will be blessed.