If God wants the best for mankind, why allow Satan to exist? Why not just destroy him, now? This article will analyze the various reasons for God keeping Satan around, even though He doesn't have to.
Satan is a created being (Ezekiel 28:12-19), who like all other created beings, depends on God for every moment of existence. He hates mankind, and is pure evil, but God ultimately allows him to exist to fulfill His purposes.
From the Bible, we can see that:
These things are all in the will of God. God isn't capricious - He has a definite, valid reason for allowing believers to be tempted, and chastened via Satan. It ultimately works to their good (Romans 8:28).
Satan's interactions with the lost are used by God either as a punishment, or they serve as a wake-up call. Again, God is not capricious or uncaring, and everything is measured, and just.
Even though Satan has his own will, and evil plans, he ultimately must receive permission from God in order to act.
We see this dynamic in Scripture:
Besides the quintessential example of Job, we have another instance where someone is turned over to Satan for temptation, with the express approval of God:
2 Samuel 24:1
1 And again the anger of the Lord was kindled against Israel, and he moved David against them to say, Go, number Israel and Judah.
1 Chronicles 21:1
1 And Satan stood up against Israel, and provoked David to number Israel.
In one account, God is said to provoke David. In the other account, though, we learn God turned David over to Satan for temptation, and that was how the work of the judgement was actually accomplished. God used Satan to reveal the wickedness that David already had in his heart.
This is exemplary of the fact that Satan is, ultimately, a tool for God. If that sounds odd, the following case study may help you understand why a tool like that makes sense, and fits well within God's plan and justice system on earth.
It's estimated that around 30 million Chinese people died in the Great Leap Forward - which was a period of disastrous programs from the Chinese Communist government in the years 1958-1962. This is but a fraction of the total amount of death, suffering, repression, and so on, that has resulted from the Chinese Communist Party coming to power in China.
At the same time, we see from Scripture that God (Daniel 4:17, Proverbs 21:1) and the Devil (Matthew 4:8-9, Luke 4:5-7, Ephesians 6:12) are said to control who is in power in governments. How? We've already discussed how - God either gives a nation to Satan for punishment, or approves/rejects Satan's suggestions for who to let take power.
So, why did God allow Satan to put the Chinese Communist Party in power? Why, when He knew all the suffering that would result?
The answer is, it was a punishment on the Chinese people for persistently rejecting God. They killed missionaries, they rejected the Gospel in favor of Buddhism and Paganism, and they mocked Christianity for centuries. They didn't want God, they wanted Marxism, so God allowed them to get Mao Zedong. And, Satan was used in that operation, to great effect.
Did the Chinese people repent, and turn to Christ? No, they didn't. So, we still see Satan's scourge on China - a polluted, corrupt, violent nation, hundreds of millions of abortions which have destroyed their demographics, poverty, relentless government oppression, famine, natural disasters on a tremendous scale - why? Because they've rejected God, and continue to reject God, and so have been turned over to Satan.
That is at least one reason the Devil is allowed to exist. He is used as a judgment on those who have rejected God, and have grown to hate God. If that makes you bristle, it's probably been a little while since you interacted with those who truly hate God, and mock the Bible. It's just, and deserved, and God is righteous to punish such people.
Ultimately, thankfully, the Devil will cease to exist. Once the Millennium is over, and he has his last hoorah (Revelation 20:7-8), he will be thrown into Hell for the final time (Revelation 20:10), as his usefulness will be finished.
The Devil will then eventually be destroyed (Ezekiel 28:13-19):
Hebrews 2:14
14 Forasmuch then as the children are partakers of flesh and blood, he also himself likewise took part of the same; that through death he might destroy him that had the power of death, that is, the devil;
So, the Devil's role is temporary, because when the earth is remade (Revelation 21:1), with God the Father ruling (1 Corinthians 15:24), there will be no more use for a being like the Devil.
The Devil is allowed to exist, because he ultimately serves the purpose of God – to punish the wicked, and prove the faith of the righteous. He does not have unbridled power, but is instead kept on a leash by God, and one day, he will be destroyed.