How Could the Angels Fall?

 Illustration for John Milton’s “Paradise Lost“ by Gustave Doré, 1866

Catechism of the Catholic Church:

392 Scripture speaks of a sin of these angels.²⁶⁹ This "fall" consists in the free choice of these created spirits, who radically and irrevocably rejected God and his reign. We find a reflection of that rebellion in the tempter's words to our first parents: "You will be like God."²⁷⁰ The devil "has sinned from the beginning"; he is "a liar and the father of lies".²⁷¹

393 It is the irrevocable character of their choice, and not a defect in the infinite divine mercy, that makes the angels' sin unforgivable. "There is no repentance for the angels after their fall, just as there is no repentance for men after death."²⁷²
 
394 Scripture witnesses to the disastrous influence of the one Jesus calls "a murderer from the beginning", who would even try to divert Jesus from the mission received from his Father.²⁷³ "The reason the Son of God appeared was to destroy the works of the devil."²⁷⁴ In its consequences the gravest of these works was the mendacious seduction that led man to disobey God.

395 The power of Satan is, nonetheless, not infinite. He is only a creature, powerful from the fact that he is pure spirit, but still a creature. He cannot prevent the building up of God's reign. Although Satan may act in the world out of hatred for God and his kingdom in Christ Jesus, and although his action may cause grave injuries - of a spiritual nature and, indirectly, even of a physical nature- to each man and to society, the action is permitted by divine providence which with strength and gentleness guides human and cosmic history. It is a great mystery that providence should permit diabolical activity, but "we know that in everything God works for good with those who love him."²⁷⁵

414 Satan or the devil and the other demons are fallen angels who have freely refused to serve God and his plan. Their choice against God is definitive. They try to associate man in their revolt against God.  

269 Cf. 2 Pet 2:4.
270 Gen 3:5.
271 1 Jn 3:8; Jn 8:44.
272 St. John Damascene, De Fide orth. 2,4: PG 94,877.
273 Jn 8:44; cf. Mt 4:1-11.
274 1 Jn 3:8.
275 Rom 8:28.

Catechism of the Council of Trent:

Satan presiding at the Infernal Council - 1824.  Painting by John Martin

Moreover, He created out of nothing the spiritual world and Angels innumerable to serve and minister to Him; and these He enriched and adorned with the admirable gifts of His grace and power.

That the devil and the other rebel angels were gifted from the beginning of their creation with grace, clearly follows from these words of the Sacred Scriptures: He (the devil) stood not in the truth. On this subject St. 42 Augustine says: In creating the Angels He endowed them with good will, that is, with pure love that they might adhere to Him, giving them existence and adorning them with grace at one and the same time. Hence we are to believe that the holy Angels were never without good will, that is, the love of God.

As to their knowledge we have this testimony of Holy Scripture: Thou, my Lord, O king, art wise, according to the wisdom of an angel of God, to understand all things upon earth.' Finally, the inspired David ascribes power to them, saying that they are mighty in strength, and execute his word; and on this account they are often called in Scripture the powers and the armies of the Lord.

But although they were all endowed with celestial gifts, very many, having rebelled against God, their Father and Creator, were hurled from those high mansions of bliss, and shut up in the darkest dungeon of earth, there to suffer for eternity the punishment of their pride. Speaking of them the Prince of the Apostles says: God spared not the angels that sinned, but delivered them, drawn by infernal ropes to the lower hell, unto torments, to be reserved unto judgment.