There was a time when all the universe was in harmony with the Love of God.
Everyone was aware of the great love that God has for them. This unity, however, was disturbed by the rise of sin in the heart of Lucifer, whom we now call the Devil and Satan.
Lucifer was created perfect.
“Thou wast perfect in thy ways from the day that thou wast created, till iniquity was found in thee.” (Ezekiel 28:15)
Lucifer comes from the Hebrew word "heylel" (הילל) which is from the word "halal"(הלל) meaning "to shine" or "give light". The word "heylel" (הילל), translated as "Lucifer", only appears in one place in the Bible and means "the morning star".
“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!” (Isaiah 14:12)
Lucifer was perfect when God created him. He loved our Almighty God with all his heart, all his soul and all his mind. However, there came a time when “iniquity was found” in him.
"Thou wast perfect in thy ways from the day that thou wast created, till iniquity was found in thee." (Ezekiel 28:15)
What was this iniquity?
Concerning Lucifer, God said, “Thine heart was lifted up because of thy beauty, thou hast corrupted thy wisdom by reason of thy brightness.” (Ezekiel 28:17)
"Thou art the anointed cherub that covereth; and I have set thee so: thou was upon the holy mountain of God; thou has walked up and down in the midst of the stones of fire." (Ezekiel 28:14)
"The anointed cherub that covereth" means that he was assigned a position over all other angels. "Covereth" is translated from the word "cakak" (סכך) which means to join together, protect and cover over (as a mother hen to its chicks).
Little by little Lucifer became more proud of his position in the Heavenly courts, he had the privilege of standing on the holy mountain of God, he walked up and down in the midst of fire before the Almighty God. And although his glory came from God, he began to believe it was his own; pride grew in his heart.
Lucifer's pride continued to grow to the point that he desired to be first in power and authority in heaven. He began to value a higher position in the heavenly courts and thought it robbery to have the Son of God over him. He wanted rulership of heaven and its inhabitants; and to this end he won a third of the angels to his side.
Next to Christ, Lucifer was the most honored of God. He stood highest in power and glory among all of heaven; first of the covering cherubs, holy and undefiled, full of wisdom and beauty. There was only One that was higher in position than he before God.
All the angels, including Lucifer and Christ, worship the Lord God. God, Himself, laid out the pattern to be held in heaven. But now, Lucifer allows jealousy for the position that belongs only to Christ to prevail. Instead of the Father and Son, Lucifer now sought to make himself equal (and even higher), as the Father made His Son equal.
How is the Son (Christ) equal to the Father (God)?
The reason for the Christ's equality is because he is "the brightness of glory, and the express image of his person, and upholding all things by the word of his power, when he had by himself purged our sins, sat down on the right hand of the Majesty on high; being made so much better than the angels, as he hath by inheritance obtained a more excellent name than they." (Hebrews 1:3,4)
Inheritance sometimes means that something, as a quality, characteristic, or other immaterial possession, received from progenitors or predecessors as if by succession. In most cases, this usually happens when something is passed down from one generation to another. In the case of God, He passed down a more excellent name to His Son; namely "deity or god" and the "brightness of glory". (Note: Lucifer also had a "brightness", but his led to iniquity; see Ezekiel 28:17; also note, the word "his" is an inserted word by the JKV Bible translators, I've removed the word above for clarity.)
"For unto which of the angels said he at any time, Thou art my Son, this day have I begotten thee? And again, I will be to him a Father, and he shall be to me a Son?" (Hebrews 1:5)
Lucifer was not around when the Son of God (Christ) was brought forth (begotten) of the Father (Lord God). In fact, nothing was. It is written about the Son, "All things were made by him; and without him was not any thing made that was made." (John 1:3)
"But to us there is but one God, the Father, of whom are all things, and we in him; and one Lord Jesus Christ, by whom are all things, and we by him." (1 Corinthians 8:6)
"For by him were all things created, that are in heaven, and that are in earth, visible and invisible, whether they be thrones, or dominions, or principalities, or powers: all things were created by him, and for him" (Colossians 1:16)
What wisdom was corrupted?
Lucifer could have stayed in favor of God. He could still have the love and honor of all the angels, exercising the powers God gave him to bless others and glorify the Creator. But his heart became proud and his wisdom became corrupt.
"Thine heart was lifted up because of thy beauty, thou hast corrupted thy wisdom by reason of thy brightness." (Ezekiel 28:17)
"Thou has set thine heart as the heart of God." (Ezekiel 28:6)
"thou hast said, ... I will exalt my throne above the stars of God: I will sit also upon the mount of the congregation... I will ascend above the heights of the clouds; I will be like the Most High." (Isaiah 14:13,14)
Lucifer endures to win the service and homage of the host of heaven to himself, coveting the honor and power that the Father has given to His Son alone. He didn't understand why he couldn't have that same privilege. He didn't want to accept that Christ could be equal with God but not himself. He declares that Christ is unfair and that God's government is unjust.
It was this abnormal ambition that led him to spread seeds of doubt among the faithful angels. The perfect harmony of heaven having been broken, Lucifer succeeded in getting one third of the angelic host to accompany him in his rebellion.
"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." (Revelation 12:4)
"And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels, And prevailed not; neither was their place found any more in heaven. 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." (Revelation 12:7-9)
It was Lucifer’s lie from the beginning that God was not as loving and fair as He had declared of Himself. Lucifer thought he could do a better job than God as ruler of the universe. At one time Lucifer believed that God was loving, kind, unselfish and just; and while in this condition, Lucifer was perfect. But as pride swelled within his heart, then iniquity was found in him. Lucifer began to doubt God’s love and the justice of His government, he spread this seed of doubt to others and as he did so, Lucifer began to believe his own lie; that he could do better than God.
Sin began with a disbelief in God’s love and law through the highest created being; Lucifer.
Sin to run its course
Satan's rebellion was to be a lesson to the universe through all coming ages—a perpetual testimony to the nature of sin and its terrible results. The working out of Satan's rule, its effects upon both men and angels, would show what must be the fruit of setting aside the divine authority. It would testify that with the existence of God's government is bound up the well-being of all the creatures He has made. Thus the history of this terrible experiment of rebellion was to be a perpetual safeguard to all holy beings, to prevent them from being deceived as to the nature of transgression, to save them from committing sin, and suffering its penalty. (PP 42.4)