he cast him into the bottomless pit
Having unlocked the abyss, the angel casts Satan into it. The picture is of all authority being with the angel and Satan as his helpless prisoner. See commentary on Revelation 20:1.
shut him up, and set a seal on him
Shut him up is ἔκλεισε αὐτον [ekleise auton] : he locked him. Only the TR text has him (αὐτον [auton] ). Set a seal on him is ἐσφράγισεν ἐπάνω αὐτοῦ [esphragisen epanō autou] : he sealed over or upon him, which can also denote having authority over the dragon.1 In the MT and NU texts, it is the abyss which is shut and sealed, not the dragon himself. In any case, the intended result is the same. Satan now has three strikes against him, he is: (1) bound, (2) shut up, (3) sealed in his prison. The word for sealed, ἐσφράγισεν [esphragisen] , is the same word which describes sealing elsewhere in the book of Revelation (Rev. Rev. 7:3-8+; Rev. 10:4+; Rev. 20:3+; Rev. 22:10+).
Examples of sealing elsewhere in Scripture indicate its complete effectiveness:
The angels treatment of Satan corresponds to Isaiahs prediction that disobedient angels would be punished and imprisoned:
The earth is violently broken, the earth is split open, the earth is shaken exceedingly. The earth shall reel to and fro like a drunkard, and shall totter like a hut; its transgression shall be heavy upon it, and it will fall, and not rise again. It shall come to pass in that day That the LORD will punish on high the host of exalted ones, and on the earth the kings of the earth. They will be gathered together, as prisoners are gathered in the pit, and will be shut up in the prison; after many days they will be punished. (Isa. Isa. 24:19-22) [emphasis added]First, they are imprisoned, and after many days they receive their final punishment. This corresponds to the age of the Millennial Kingdom during which Satan and his angels are locked away. After his release and final rebellion (Rev. Rev. 20:7-10+), he will meet his final punishment.
so that he should deceive the nations no more
The first human target of his deception was Eve in the garden (1Ti. 1Ti. 2:14). Since then, he has deceived nations throughout history, but never more so than his final attempt at victory during the Great Tribulation (Rev. Rev. 12:12+). He restored the Beast from death so that all the world would worship him (Rev. Rev. 13:3+). He spoke by the mouth of the False Prophet (Rev. Rev. 13:11+) and empowered him to deceive the earth dwellers to their doom by taking the mark of the Beast (Rev. Rev. 13:14+, Rev. 13:16+; Rev. 14:9-11+). He carried the Harlot as she rode throughout history upon his seven heads (Rev. Rev. 17:3+ cf. Rev. Rev. 12:3+) and made the inhabitants drunk with her fornicating wine (Rev. Rev. 17:2+) and sorcery (Rev. Rev. 18:23+). He controlled the three unclean spirits which were sent out to gather the kings to the Campaign of Armageddon (Rev. Rev. 16:13-14+) which led them to the slaughter (Rev. Rev. 19:21+).
His deceptive activities, which affect both believers and unbelievers, are a fact of the Church age:
But I fear, lest somehow, as the serpent deceived Eve by his craftiness, so your minds may be corrupted from the simplicity that is in Christ. (2Cor. 2Cor. 11:3).
For such are false apostles, deceitful workers, transforming themselves into apostles of Christ. And no wonder! For Satan himself transforms himself into an angel of light. Therefore it is no great thing if his ministers also transform themselves into ministers of righteousness, whose end will be according to their works. (2Cor. 2Cor. 11:13-15)A plain reading of the passage indicates that Satan is unable to deceive while he is locked away. As soon as he is released, he immediately goes out to deceive the nations (Rev. Rev. 20:8+, Rev. 20:10+), which he had been completely unable to do while in the abyss. If this language does not mean that the immobilization of Satan is complete, so far as his deception of the nations (Grk. ethne) is concerned, then there is no way to express the idea.2
This is his pattern: misrepresentation of truth through deception so those who respond to his promises always wind up with unforeseen liabilities which attend participation in his schemes. His two greatest tools are temptation and compromise. See commentary on Revelation 13:14.
till the thousand years were finished
What an amazing time of blessing this will be! Satan and his demonic realm will be rendered completely inoperative during the coming earthly kingdom of God. But this great blessing also has a flip side: in the removal of the great tempter is the removal of a convenient excuse by which men hide their own rebellious nature. And this, it would seem, is part of Gods plan in locking Satan away for the duration of the Millennial Kingdomto show man his utter incapability of obedience to God, even in the midst of ideal conditions and in the absence of the influence of the serpent of old.
But after these things he must be released for a little while.
After the thousand years have expired, he is released to deceive the nations one final time. Here we see the sovereignty of God Who uses all things to achieve His ultimate ends. Satan is no less a tool of God in his rebellion than in his obedience. Although God is not the author of sin, His sovereignty over the affairs of history is not the least threatened by the disobedience of His creatures. See commentary on Revelation 20:7.
1 Frederick William Danker and Walter Bauer, A Greek-English Lexicon of the New Testament and Other Early Christian Literature (Chicago, IL: University of Chicago Press, 2000), 283.