Why did God send Lucifer down to earth?

Q: Why did God send Lucifer down to earth to live and rule amongst his beloved creations? (New Jersey)

A: I don't think we can say that God truly sent the devil -- also known as Lucifer, or later as Satan -- down to earth in quite the way your question envisions. While the devil was cast out of God's direct presence in heaven, this did not happen because God actively wanted Satan to have sway over his creatures.

We can read a poetic description of Lucifer being forced out of heaven in the Book of Revelation:

"Then war broke out in heaven; Michael and his angels battled against the dragon. The dragon and its angels fought back, but they did not prevail and there was no longer any place for them in heaven. The huge dragon, the ancient serpent, who is called the Devil and Satan, who deceived the whole world, was thrown down to earth, and its angels were thrown down with it" (Rv 12:7-9).

In St. Luke's Gospel, it seems that Jesus himself makes a brief and somewhat mysterious reference to this same event when he says to his disciples: "…I have observed Satan fall like lightning from the sky" (Luke 10:18).

The Catechism of the Catholic Church fills in some of the more technical details of how to understand this bit of celestial pre-history, noting that "the Church teaches that Satan was at first a good angel, made by God: The devil and the other demons were indeed created naturally good by God, but they became evil by their own doing. Scripture speaks of a sin of these angels. This 'fall' consists in the free choice of these created spirits, who radically and irrevocably rejected God and his reign" (CCC 391-392).

In other words, Lucifer was created by God as a good angel, meant to fulfill a properly angelic mission of praising God's glory and communicating God's word. But Lucifer, despite having perfect freedom and insight, nevertheless chose to reject God's plan, and convinced many other angels to do likewise. These angels' fall from heaven was the natural consequence of their own free decisions to separate themselves from God; it was certainly not, as the Catechism puts it: "a defect in the infinite divine mercy" (CCC 393). Their fall was also not any kind of backwards evil divine mission, which is why it would not be accurate to describe the devil and the bad angels as being "sent to earth" by God.

That said, here are a few passages in the Gospel which suggest that Satan is the "ruler of this world." For example, prior to Jesus beginning his public ministry, Satan tempted Jesus in the desert by offering Jesus "all the kingdoms of the world" if Jesus would bow down and worship him (See Luke 4:5-7). However, the idea that Satan is the "ruler" or "prince" of this world only means that Satan has some command over the passing things of this present life and is thus able to tempt us with the "empty promises" we renounce at our baptism. It does not mean that Satan has any true power over God's cosmic ordering of the universe, time and history.

The Catechism echoes this point when it tells us: "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" (CCC 395).

And when Jesus refers to the worldly reign of Satan in the Gospel of John, he does so only to indicate that this reign will soon be destroyed. Looking ahead to his imminent passion, death, and resurrection, Jesus states: "Now is the time of judgment on this world; now the ruler of this world will be driven out. And when I am lifted up from the earth, I will draw everyone to myself" (Jn 12:31-32).