Demons

In addition to great intelligence, angels were also created with free will, and were given one opportunity to choose between the Good and the apparent good. Why the "apparent good?" Because there are two ways to sin: a) to sin out of ignorance or error in doing something inherently wrong (culpability for sins of this type is mitigated by the ignorance that allowed it), and b) to sin by free will in choosing to do something that is good in itself, but in an inordinate, unmeasured, unregulated way that doesn't allow for due consideration of what is involved. The great intellect of the angels precluded their choosing an inherent evil -- but it didn't preclude their choosing their own good (which is good in itself) -- but in a manner insubordinate to what God wills.

So, at some time after their creation and before the creation of man, the angels had a choice between the Good and the apparent good. One of the angels -- a most beautiful, illustrious angel who had the rank of Cherub and whose state was that of "Lucifer," or "Light-Bearer" -- chose the latter. He wanted to be as God but without subordinating himself to God (see Isaias 14:11-15 below). Some theologians and Fathers maintain that the coming Mystery of the Incarnation was revealed to the angels, and that Lucifer and company rebelled at the thought of having to pay homage to One Who would take on a human nature, a nature lesser than their own. In any case, whether the sin of Lucifer is best described as pride (St. Thomas Aquinas) or spiritual lust (Bl. Don Scotus), Lucifer chose wrongly and fell, and other angels fell with him. The Epistle of Jude describes what happened:

Jude 1:6 6
And the angels who kept not their principality, but forsook their own habitation, he hath reserved under darkness in everlasting chains, unto the judgment of the great day.

Apocalypse 12:7-9
And there was a great battle in heaven, Michael and his angels fought with the dragon, and the dragon fought and his angels: And they prevailed not, neither was their place found any more in heaven. And that great dragon was cast out, that old serpent, who is called the devil and Satan, who seduceth the whole world; and he was cast unto the earth, and his angels were thrown down with him.

The words of the Prophet Isaias, though directly referencing the King of Babylon, have been understood by the Fathers to describe typologically the fall of the Lucifer:

Yes, there was a great moment of choice for the angels, all of whom were created good. It's always to be remembered that God is never the Author of evil. He may passively allow evil, but never creates it or positively wills it. Anyway, so some angels remained with God and are the beings we typically refer to as "angels"; the rest became the fallen angels we usually refer to as "demons" or "devils," and whose leader is Lucifer, or Satan -- the Devil. These demons are sentenced to Hell for eternity, but are allowed powers on earth until the Final Judgment, when they will be finally cast into Hell, never to return.

Satan and his minions have been with us since the beginning of human history. Satan was there, in the guise of a serpent, in the Garden of Eden, tempting Adam and Eve to rebel against God, and he has been with us ever since, a liar and murderer, doing all in his power to get us to reject God and follow his demons into Hell. Just as Christ is Life, the Evil One is death -- the death of the body, which only became a part of natural world after the Fall, and the death of the soul in that souls who follow him will be forever cut off from our God Who is Life.

He even tempted Lord Christ Himself. From the Gospel of St. Matthew 4: 1-11 (and also related in Mark 1:12-13 and Luke 4:1-13):

Then Jesus was led by the spirit into the desert, to be tempted by the devil. And when he had fasted forty days and forty nights, afterwards he was hungry. And the tempter coming said to him: If thou be the Son of God, command that these stones be made bread. Who answered and said: It is written, Not in bread alone doth man live, but in every word that proceedeth from the mouth of God.

Then the devil took him up into the holy city, and set him upon the pinnacle of the temple, And said to him: If thou be the Son of God, cast thyself down, for it is written: That he hath given his angels charge over thee, and in their hands shall they bear thee up, lest perhaps thou dash thy foot against a stone. Jesus said to him: It is written again: Thou shalt not tempt the Lord thy God.

Again the devil took him up into a very high mountain, and shewed him all the kingdoms of the world, and the glory of them, And said to him: All these will I give thee, if falling down thou wilt adore me. Then Jesus saith to him: Begone, Satan: for it is written, The Lord thy God shalt thou adore, and him only shalt thou serve.

Then the devil left him; and behold angels came and ministered to him. ¹

Just as he tempted Christ, he tempts us. When tempting Christ, he appealed first to weakness of the flesh. Then he appealed to weakness that comes from the desire to be respected by the world. Finally, he appealed to spiritual pride. And it's in those same ways the Evil One tempts us. Eating that one piece of pie too many. Taking the larger piece of pie when there are two pieces left and someone else wants a slice. Looking at a person of the sex you're attracted to and turning him or her, mentally, into an object of lust. Inordinate anger at being cut off in traffic or when watching as someone takes the parking space you want. Doing nothing when you're called to act. Wishing another will fail because you want what he has and are enraged at his success. Not admitting you're wrong when you know you are. These acts are all examples of the Seven "Deadly" or "Capital" Sins: Pride, Greed, Lust, Anger, Gluttony, Envy, and Sloth. We refrain from falling into those sins by our striving for their contrary virtues: Humility, Liberality, Chastity, Meekness, Temperance, Brotherly Love, and Diligence. And we attain those virtues by practice, by making habits of them -- first by willing ourselves to do so and then using discipline and acting on our will, doing the right things at each instance those occasions of sin come up, repenting and confessing when we fail. We're helped in all this by receiving the Sacraments, praying, doing what God tells us (most especially loving Him and loving our neighbors), forgiving others, avoiding "occasions of sin" (those situations which make it too easy for us to fall into sin), praying to the Saints (especially St. Michael) and our Guardian Angel to pray for and protect us, and making use of sacramentals. I will write more about all of these on the "Spiritual Warfare" page in this section.

Satan is pure hatred. He is contempt for all that is Good, True, and Beautiful. The utter loathing he has for God, for you, for me, has no bounds. Think of the most beautiful thing you can imagine -- a lovely, innocent newborn baby, perhaps, full of potential, trusting, soft, sweet, and vulnerable. And now imagine the most horrific, unspeakable things happening to that child. Rape, violence, torture. That is the spirit of Satan. He "wanders throughout the world, seeking the ruin of souls," as the prayer to St. Michael goes. He wants our souls. He wants your soul. And he does all he can to get it. And aside from normal, everyday temptations, there are other ways in which the devils torment us...

Footnotes:

¹ St. Thomas Aquinas, in his "Summa Theologica," points out something interesting about the ways in which the Evil One tempted Christ. He compares them to the way he tempted Adam. He writes,

For at first he enticed his [Adam's] mind to consent to the eating of the forbidden fruit, saying: "Why hath God commanded you that you should not eat of every tree of paradise?"

Secondly he tempted him to vainglory by saying: "Your eyes shall be opened."

Thirdly, he led the temptation to the extreme height of pride, saying: "You shall be as gods, knowing good and evil."

This same order did he observe in tempting Christ. For at first he tempted Him to that which men desire, however spiritual they may be--namely, the support of the corporeal nature by food.

Secondly, he advanced to that matter in which spiritual men are sometimes found wanting, inasmuch as they do certain things for show, which pertains to vainglory.

Thirdly, he led the temptation on to that in which no spiritual men, but only carnal men, have a part--namely, to desire worldly riches and fame, to the extent of holding God in contempt. And so in the first two temptations he said: "If Thou be the Son of God"; but not in the third, which is inapplicable to spiritual men, who are sons of God by adoption, whereas it does apply to the two preceding temptations.