Theology question: why hasn't God stopped Satan and his demons?

The Bible presents God's kingdom as gradually growing, but not instantly defeating the Kingdome of Satan. The Devil took kingship of the world because he tempted the first humans to sin. When they fell they fell into sin, death, hell and under the bondage of the malicious lordship of Satan. (Genesis 3:1)

Gradually over history God established a new kingdom. In Abraham he called out a people to live under his rule. (Genesis 12) Then in Christ he made a new heaven and earth creating a new kingdom (Isaiah 65). This is why Jesus always said the 'Kingdom of God is like...' (Math 13) and John the Baptists said the kingdom of God was at hand. (Mathew 3:2)

Now when Jesus did arrive the Devil was enlivened in terms of Biblical descriptions of his presence in the world (Math 4:1) and all his minions. Before Christ there is very little spoken about the devils or the Devil. (Math 8:16)

Now after Jesus rose, he promised to return in judgment. (2 Timothy 4:1) This is the final building of his kingdom when sin, death, hell and Devil will be bound forever. (Rev 21:4)

So you see the question you asked is not why still the Devil, but why sin, why disease, why sorrow, why not heaven now?

The answer is God does all things according to his own eternal plan and this apparently includes a gradual salvation of humanity in Christ. (Eph 1:3)

In addition, to all the answers: it was God's plan to make all the creatures that have a mind, e.g. human beings, angels and devils, free and give them a free will. Othwerise, there would be no sinners and no devils.

Stopping the angel from becoming a devil would contradict this plan.

The reason that God did not simply destroy evil is because the suffering it has caused has allowed for the glory of God to increase.

It is through his suffering that Jesus attained perfection (completeness).

In bringing many sons and daughters to glory, it was fitting that God, for whom and through whom everything exists, should make the pioneer of their salvation perfect through what he suffered. (Hebrews 2:12)

Most Christian groups agree that in order for a sinner to be redeemed and made perfect before God, he needs

1. Forgiveness of sin
2. Justification under the law
3. Sanctification of the flesh

Without these three "corrections" to his former state, a person can not enter into the Kingdom of God, because

Nothing impure will ever enter it, nor will anyone who does what is shameful or false, but only those whose names are written in the Lamb's book of life. (Revelation 21:27)

Had God simply destroyed the evil and all of the wicked things that it wrought, this would have included us because in our former ways, we were enemies of God, even if we didn't realize it. He chose not to destroy us, but instead to redeem us because God is good, and he loves us. It is also the suffering of Christ that has allowed us to become righteous. He chose willingly to suffer evil on our account, so that he could give his righteousness to us.

To this you were called, because Christ suffered for you, leaving you an example, that you should follow in his steps.

"He committed no sin, and no deceit was found in his mouth.”

When they hurled their insults at him, he did not retaliate; when he suffered, he made no threats. Instead, he entrusted himself to him who judges justly.“He himself bore our sins” in his body on the cross, so that we might die to sins and live for righteousness; “by his wounds you have been healed.” (1 Peter 2:21-24)

For if, while we were God's enemies, we were reconciled to him through the death of his Son, how much more, having been reconciled, shall we be saved through his life! (Romans 5:10)

So instead of just wiping out evil, to allow a way for us to be restored and redeemed to a position in communion with God that satisfies the three conditions I mentioned above, God made a plan of redemption that included his own suffering and the suffering of his Son so that he could know us, and so that we could be like him,:

But now apart from the law the righteousness of God has been made known, to which the Law and the Prophets testify. This righteousness is given through faith in Jesus Christ to all who believe. (Romans 3:21)

As His divine power has given to us all things that pertain to life and godliness, through the knowledge of Him who called us by glory and virtue, by which have been given to us exceedingly great and precious promises, that through these you may be partakers of the divine nature, having escaped the corruption that is in the world through lust. (2 Peter 1:2-4)

So, in summary, because God did not just destroy evil, he was able to use the suffering caused by evil to bring about a more perfect solution, and with that more glory to himself and Jesus, and to redeem mankind to himself through Jesus.

As an ending note: A major contention between Judaism and Christianity is that Jews do not acknowledge that the true Messiah would suffer and die, while Christians maintain that the Messiah had to suffer and die (cf. Acts 17:3). Many Jewish websites and sources mock the true Messiah Jesus, referring to him as "the one who failed" as evidenced by his suffering. Ironically, this is evidence all the more to Christians that Jesus is indeed the Messiah, since they interpret many prophecies from the Hebrew old testament to imply that the Messiah would suffer and be rejected, specifically by the Jews (cf. Psalm 118:22).

The answer to your question is that God is a perfect teacher with a perfect sense of justice.

I will illustrate and then explain: (this is a completely hypothetical situation)

Imagine that there is a flight from the US to Switzerland. The pilot is very good, in fact he is a perfect pilot. He has more knowledge and experience that anyone else in his field. Now after getting the jet into the air, one of his co-pilots decides that he can fly that plane better. He charges that the pilot doesn't know what he is doing and that he would make a better pilot. What does the pilot do? The pilot knows that he can fix any mistakes his co-pilot makes and by letting the co-pilot fly for a little while he will prove to everyone that there is no better pilot than he.

So he hands over the controls and gives the co-pilot a set amount of time to prove his accusations. The pilot sits back and watches, not wanting to help because that would just prove his co-pilot right. Well his inexperienced co-pilot is soon heading off course, in a direction that the pilot never intended. The pilot calmly sends his oldest friend and worker to tell everyone aboard the jet that everything is under control and will be fixed shortly.

Eventually the co-pilot's time runs out and the flight is way off course. He has proved himself wrong. The pilot then takes control of the jet back, as he has promised. He then makes some adjustments to steer them all in the correct direction. He lands the plane at its destination as was intended.

The pilot is God and the co-pilot is Satan. God's intention for the earth never changed, just as that aircraft's destination had not changed. Isaiah 45:18

"For this is what Jehovah says, The Creator of the heavens, the true God, The One who formed the earth, its Maker who firmly established it, Who did not create it simply for nothing, but formed it to be inhabited: “I am Jehovah, and there is no one else."

Psalm 37:29

"The righteous will possess the earth, And they will live forever on it."

Satan charged that God is a liar, questioned man's motive for loving God (letting him be pilot), and sought a position higher than God's. Genesis 3:3-4

"But God has said about the fruit of the tree that is in the middle of the garden: ‘You must not eat from it, no, you must not touch it; otherwise you will die.’” 4 At this the serpent said to the woman: “You certainly will not die."

Satan then questions mans motive and integrity at Job 1:9-12

At that Satan answered Jehovah: “Is it for nothing that Job has feared God?10 Have you not put up a protective hedge around him and his house and everything he has? You have blessed the work of his hands, and his livestock has spread out in the land. 11 But, for a change, stretch out your hand and strike everything he has, and he will surely curse you to your very face.” 12 Then Jehovah said to Satan: “Look! Everything that he has is in your hand. Only do not lay your hand on the man himself!”

Isaiah 14:13-14

"You said in your heart, ‘I will ascend to the heavens. Above the stars of God I will lift up my throne, And I will sit down on the mountain of meeting, In the remotest parts of the north. 14 I will go up above the tops of the clouds; I will make myself resemble the Most High.’"

Just like that pilot, God is letting Satan take control of the world to prove his accusations.

1 John 5:19

"We know that we originate with God, but the whole world is lying in the power of the wicked one."

God recognizes that when Satan rules, Satan will go off course just like that jet. Satan teaches us false things about god. He distorts true worship. He imprints qualities of himself in man. 2 Timothy 3:2-5

"For men will be lovers of themselves, lovers of money, boastful, haughty, blasphemers, disobedient to parents, unthankful, disloyal,3 having no natural affection, not open to any agreement, slanderers, without self-control, fierce, without love of goodness,4 betrayers, headstrong, puffed up with pride, lovers of pleasures rather than lovers of God, 5 having an appearance of godliness but proving false to its power"

God comforts us through his son Jesus. Jesus teaches us about what is happening and what God promises for the future. 1 John 5:20

"But we know that the Son of God has come, and he has given us insight so that we may gain the knowledge of the one who is true."

1 John 3:8

"For this purpose the Son of God was made manifest, to break up the works of the Devil."

God is letting this all happen for a reason. There are other watchers, not just Satan. Satan rebelled and brought other angels out from God's house. By letting things play out this way, God will prove for all time that he the only one fit to rule. In a court case this would be considered a "precedent". In case this question should ever come up again, God has a precedent to show us he is the best ruler. Precedent definition

": a similar action or event that happened at an earlier time, : something done or said that can be used as an example or rule to be followed in the future"

Satan's time is almost up. Satan has proved himself a liar and unfit to rule. God will be taking back control over the world. Jehovah God will then restore the world to its original purpose; That is: a paradise earth and on it perfect people who never die. This is basically what the bibles message is, shortened and paraphrased.

Aquinas covers this to an extent, in http://www.newadvent.org/summa/1064.htm, article 4.

Angels stand between us and God. Through God's order of things the superior (angels/God) help to improve the welfare of the inferior (us), and this can be done in one of two ways.

First, we can just be good, and with the help of angels be protected, but there is also that some will wrestle with demons, and through these trials will become better people.

If the demons did not serve this purpose then they would have no place in the natural order, and so could be destroyed.

Since they have a purpose, destroying them, or imprisoning all of them is counter to the natural order, so is something that God won't do.

If you are interested in what Augustine wrote about why demons are in our atmosphere you can look at The literal meaning of Genesis, Volume 1, reflections on the fifth and sixth days, chapter 10. If you look on this page, you can find the Google Books version:

http://litteralchristianlibrary.wetpaint.com/page/Penteteuch

It makes more sense when you look at it from an eternal perspective. Yes, Satan and his followers cause us a lot of trouble in this life, but our life on Earth is not about our life on Earth. It's essentially a test, to see if we will be faithful and obedient to God's commandments. But that would be a meaningless question without opposition to provide a (seemingly) good reason to not want to.

That's Satan's role in the plan. (See the first 2 chapters of Job, for example. See also 1 Corinthians 10:13, which explicitly reiterates the point demonstrated in Job, that God does not allow Satan to do certain things that we would not be able to bear.) He rebelled against God and sought to destroy God's work, but God is still able to find a useful purpose for Satan to serve. But we are assured that after the end of this world, when the time of testing and mortality is over, that Satan will be cast into hell for all eternity. (Revelation 20:10)