SATAN CAST OUT OF HEAVEN BEFORE THE PENTECOST
When Jesus says "now" in Jn 12:31, he's signaling the moment in which the prince of this world was being cast out. The word "now" he uses could refer to that particular moment, or the entire process of his crucifixion and resurrection, which would be more reasonable.
Now is the judgment of this world; now shall the prince of this world be cast out.
(Jn 12: 31)
If we read Lk 22:31, we'll see that Satan had asked the apostles to be sifted as wheat. If he asked for this, it is because he had access to God at the moment. In other words, he hadn't been cast out of Heaven yet. But nonetheless, after the crucifixion of Christ, there's no part of the New Testament saying that Satan will present himself before God, nor is such a thing induced. That leads us to think that he could no longer present himself before God to make petitions.
After the crucifixion, Satan and the demons kept tempting humans with the same ancient and divine permission they've always had, even though they were cast out of Heaven. This temptation is only in general terms, not by asking permission for a specific temptation like in Job's case, or the one of him sifting the apostles. In the two cases mentioned we see that Satan had direct access to God, because he was still in Heaven.
By knowing that Satan is called the prince of this world, it is possible to think that he was "thrown out" of Heaven during the terrestrial ministry of Christ. Why do I think this way? Because in Jn 12:31, previously read, we see that our Lord Jesus Christ speaks in the present tense, saying that "now" Satan "shall" be cast out. By saying "now", we can see that he was going to be cast out during the process of the crucifixion and resurrection of the Lord; and by using the word shall (future) we can see that during the moment he spoke, he had not been cast out yet.
So, from where was Satan cast out? It's logical to think that from Heaven, because evidently, he wasn't cast out of planet Earth. All of this concords with what was said by the Lord in Lk 10:18.
And he said unto them: I beheld Satan as lightning fall from Heaven. ( Lk 10:18 )
It's probable that the Devil could be tolerated in Heaven for some time, despite his evilness, as indicated by the first and second chapters of Job. But when he dared to rise directly against the Son of God during the terrestrial life of the Lord, by tempting him, trying to get him to sin, and lastly by enticing others to make him suffer by crucifying and assassinating him, he could no longer be tolerated. He had gotten too far, and therefore, he couldn't continue living where a resurrected Jesus, whom he mistreated and assassinated on Earth, would live and reign. It is not logical for there to be a place for him in Heaven; and due to this, he was cast down to Earth. God and the slayer of his Son could not live together under the same roof. Christ couldn't live together with Satan who tried, through sinful temptations, to separate him from his Father God forever. That's why it is logical to think that Satan was cast out of Heaven after the Lord's crucifixion.
The moment described in Rev 12:7-13 is clearly the process of Christ's crucifixion and resurrection, where twice it mentions the Devil being cast out, especially in verses 9 and 12.
7 And there was war in heaven. Michael and his angels fought against the dragon; and the dragon fought and his angels. 8 And prevailed not; neither was their place found any more in heaven. 9 And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world; he was cast out into the Earth, and his angels were cast out with him. 10 And I heard a loud voice saying in heaven: Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ; for the accuser of our brethren is cast down, which accused them before our God day and night. 11 And they overcame him by the blood of the Lamb, and by the word of their testimony; and they loved not their lives unto the death. 12 Therefore rejoice, ye heavens, and ye that dwell in them. Woe to the inhabiters of the earth and of the sea!, for the Devil is come down unto you, having great wrath, because he knoweth that he hath but a short time. 13 And when the dragon saw that he was cast unto the earth, he persecuted the woman which brought forth the man child. (Rev 12:7-13)
This passage says that the Devil, once launched to Earth, pursued the woman, something that concords with historical reality, if we admit that the woman is the assembly of the saints, The Church, and the believers of the synagogue converted to Christianity. Sure enough, the persecution was unleashed against the Church after the crucifixion and resurrection of the Lord. Remember that it was the Jews who were victims of the first persecution towards Christianity.
After being thrown out of Heaven, Satan pursued the Church. From this, we can deduce that he was thrown out of Heaven before the persecutions of the Church started, but after what Jesus Christ said in Jn 12:31, that it was now that Satan would be cast out.
Now is the judgment of this world; now shall the prince or this world be cast out. ( Jn 12:31 )
Notice how categorical the Lord was in the verse (Jn 12:31) when he said: .now shall the prince of this world be cast out. He is saying this shortly before the thirteenth chapter of John, where the long and detailed narration of the Lord's conversation with his disciples during the Last Supper begins. What I want to say with this is that there was little time left before the crucifixion and yet the Lord puts the expulsion in future tense, but a not so distant future, which is modified by the adverb now.
From all this, we can reason that the expulsion occurred after the crucifixion; which, by the way, sounds logical since God, Christ, the Holy Spirit, and those who love Jesus couldn't live together with he who assassinated Christ on Earth and tried to lose him eternally.
Another thing that helps us think that the expulsion of Satan from Heaven took place during the process of the crucifixion and resurrection of the Lord is the fact that in verse 10 of this chapter in Revelation, after saying in verse 9 that Satan and his angels had been cast out, it says that .Now is come salvation . It is not logical to think that salvation came simply because the Devil had been cast out from Heaven. What's logical is to think that salvation came only after Jesus Christ died and resurrected. Therefore, we should think that if the salvation mentioned and the expulsion are contemporary, this expulsion occurred during the process of the crucifixion and resurrection.
Also, if they mention that the persecution of the church occurred after Satan was thrown out, it's also logical to reason that it's because Satan had already been cast out from Heaven when he began the persecution of the Church. Maybe Jesus stayed on Earth 40 days after his resurrection to give time for those rebellious angels to be cast down.