But what exactly was the character or nature of Satan’s iniquity?
As suggested by 1 Timothy 3:6-7 and Ezekiel 28:17, though created perfect by God (Ezek. 28:13-15), it was conceit or pride that welled up in his heart because of his beauty and high position that led to arrogant aspirations and to his sin and fall.
In Isaiah 14:12-15 and in Ezekiel 28:12-19, we have a remarkable account of the original place which Satan once had as “Lucifer, son of the morning.” His fall from this original, exalted place, of perhaps the greatest of created angelic beings, is given in these Scriptures. These arrogant aspirations are described for us in Isaiah 14:12-17 : pride, self-will, iniquity, rebellion, and violence are the reasons.
Because of his pride and aspirations to be like God, he became God’s chief adversary (Heb. Satan). After this, he is never again called by any of these prestigious titles. Instead, he is called by terms that reflect his fallen character and hostility to God and men, like liar, murderer, Satan (adversary), the evil one, Abaddon (destruction), Apollyon (destroyer), Belial (worthless), serpent, and dragon.
Scotus, however points out that this sin was not pride properly so called, but should rather be described as a species of spiritual lust.
Although nothing definite can be known as to the precise nature of the probation of the angels and the manner in which many of them fell, many theologians have conjectured, with some show of probability, that the mystery of the Divine Incarnation was revealed to them, that they saw that a nature lower than their own was to be hypostatically united to the Person of God the Son, and that all the hierarchy of heaven must bow in adoration before the majesty of the Incarnate Word; and this, it is supposed, was the occasion of the pride of Lucifer.
Furthermore, we learn from Ezekiel 28 that Lucifer engaged in a multitude of traffic, which means “going about.” He filled heaven with violence and sinned.
“Thou has defiled thy sanctuaries by the multitude of thine iniquities, by the iniquity of thy traffic”
Thus Lucifer instigated violence and rebellion among the heavenly hosts before man was created, and those who followed him became his angels or demons. Seeking to overthrow God and rule heaven, Lucifer assembled an army of apostate angels and initiated a war in heaven.
In the book of Revelation we read about a war in heaven between Michael and the angels who remained loyal to God and the dragon, “called the Devil, and Satan,” and his angels. Then Satan and his angels were defeated by Michael, and were thrown down from heaven to hell.
“And there was war in heaven, Michael and his angels waging war with the dragon. And the dragon and his angels waged war, and they were not strong enough, and there was no longer a place found for them in heaven. And the great dragon was thrown down, the serpent of old who is called the devil and Satan, who deceives the whole world; he was thrown down to the earth, and his angels were thrown down with him.” Revelation 12:7-9