First of all, Scripture teaches us emphatically that “hell was created for Satan and his angels” in Matthew 25:41 where Jesus said, “Depart from Me, you cursed, into the EVERLASTING FIRE PREPARED FOR THE DEVIL AND HIS ANGELS” (NKJV). Satan and his angels HAVE NOT ESCAPED from Hell for they haven’t been cast into Hell yet. Just before Jesus went to the cross to defeat Satan, He said “Now is the judgment of this world; now the ruler of this world will be cast out” (John 12:31). Some have taken this to mean that after Jesus died and rose again Satan and his angels were immediately consigned to Hell. Yet this judgment is a future event that will take place in three phases. FIRST, he will be cast from heaven to earth (see Revelation 12:7-9), then from earth to the bottomless pit (Revelation 20:1-3), and finally from the earth to the lake of fire (Revelation 20:7-10). Their doom is certain and we can rest assured that “the God of peace will crush Satan under your feet shortly” (Romans 16:20).

Now we’re prepared to answer your main question: Why is it they are not serving their sentences and are causing havoc on Earth? This is a reasonable question that demands a scriptural answer. I believe one of the main reasons God allows Satan and his angels to remain free is to TEST MANKIND. God is seeking to win the hearts of men and women through the gospel of Jesus Christ for God “desires all men to be saved and to come to the knowledge of the truth. For there is one God and one Mediator between God and men, the Man Christ Jesus, who gave Himself a ransom for all” (1st Timothy 2:4-5). Satan is trying to blind men and women to the truth of the gospel as we see in 2nd Corinthians 4:3-4, “But even if our gospel is veiled, it is veiled to those who are perishing, WHOSE MINDS THE GOD OF THIS AGE HAS BLINDED, who do not believe, lest the light of the gospel of the glory of Christ, who is the image of God, should shine on them.” Will men believe God or will men believe Satan? That is the TEST and God is using Satan to see if men will “pass the test.” Sadly, many choose to be BLINDED TO THE TRUTH and thus they believe Satan’s lies. Why do they make this fatal choice? We have the answer in John 3:19-20, “And this is the condemnation, that the light has come into the world, and MEN LOVED DARKNESS RATHER THAN LIGHT, BECAUSE THEIR DEEDS ARE EVIL. For everyone practicing evil HATES THE LIGHT and does not come to the light, lest his deeds should be exposed.” In a word, MEN LOVE THEIR SIN and because of this they HATE THE LIGHT and willfully choose to remain in a state of spiritual blindness. What we are learning in these verses is that men are first BLINDED BY THEIR OWN FREE WILL and then they are FURTHER BLINDED BY SATAN who keeps them in a state of darkness by tempting them with all that the world has to offer and with false teachings.

Satan is also free to TEST BELIEVERS in order “to prove their faith.” A classic example of this is seen in the case of Job, where Satan approached God and said, “Does Job fear God for nothing? Have You not made a hedge around him, around his household, around all that he has on every side? You have blessed the works of his hands, and his possessions have increased in the land. But now, stretch out Your hand and touch all that he has, and HE WILL SURELY CURSE YOU TO YOUR FACE” (Job 1:9-11). Satan was convinced Job feared God and served Him because of the material blessings God had showered upon him and that if he were allowed to take those possessions away from Job he would “curse God to His face.” The Lord then said to Satan, “Behold, all that he has is in your power; only do not lay a hand on his person” (verse 12). So, God allowed Satan to TEST JOB and as we read on, we see that Satan stripped Job of all of his possessions, his servants and his ten children (verses 13-19). We can say (as you did in your question) that Satan caused great havoc on the Earth and in the life of God’s servant Job. How did Job react to the test? Ah, HE PASSED THE TEST, for instead of “cursing God to the face” we read that “Job arose, tore his robe, and shaved his head; and he FELL DOWN TO WORSHIP. AND HE SAID: ‘Naked I came from my mother’s womb, and naked shall I return there. The LORD gave, and the LORD has taken away; blessed by the name of the LORD.’ In all this Job did not sin nor charge God with wrong” (verses 20-22). This is but one example of how God USES SATAN TO TEST HIS PEOPLE’S FAITH. We see that Job’s 1) faith was genuine and strengthened; and 2) God was glorified through Job’s faith.

We could cite many more examples to show that God has a DEFINITE PURPOSE in allowing Satan and his angels to remain free to exert their influence over mankind; it is indeed to TEST THEM to see if they will choose to follow Satan or the Lord Jesus Christ. Yet the day is coming (as we have seen) that God’s Divine Plan in testing mankind will be over and then Satan and his angels will be “cast into the lake of fire….and they will be tormented day and night forever and ever” (Revelation 20:10).  (459.3)  (DO)