Risen from the Dust
On a bit of a darker note, and contrary to popular belief, Satan and his angels currently reside somewhere in heaven, not in hell. Despite our inclination to picture them as ruling in the underworld, this assumption is not supported by the careful analysis of scripture. Satan and his own have certainly fallen spiritually in their opposition to God, who is the truth and the light, but that's not the same as being cast down from heaven. God allows them to maintain their place in the heavens, until the season of their destruction arrives.
The opening chapter of the book of Job tells us that Satan is basically free to go where he wants, including heaven, "Now there was a day when the sons of God came to present themselves before the LORD, and Satan came also among them. And the LORD said unto Satan, Whence comest thou? Then Satan answered the LORD, and said, From going to and fro in the earth, and from walking up and down in it" (Job 1.6-7 KJV bible). During the time of the events described in Job, Satan is free to traverse either heaven or earth.
Though Satan is depicted as having free range in the bible, it is also prophesied that he will at some point be banished from heaven, and literally cast to the earth. At this time men will look upon him, "I will cast thee to the ground, I will lay thee before kings, that they may behold thee" (Ezekiel 28.17 KJV bible). Also, Isaiah 14 tells us that after he is cast down, he will be entombed in Sheol, "They will all respond and say to you, Even you have been made weak as we, You have become like us. Your pomp and the music of your harps have been brought down to Sheol; Maggots are spread out as your bed beneath you And worms are your covering" (Isaiah 14.11 NASB bible). So as to the whereabouts of Satan and his angels, the question is whether these events; their expulsion, time on Earth, and imprisonment in the Abyss (a part of Sheol), have come to pass yet?
Revelation depicts these events in detail, and also gives us some frame of reference for when they will happen. Revelation 12 tells us that after Satan is cast out of heaven (along with his angels), he will persecute the woman for a time, times, and a dividing of time, "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...And when the dragon saw that he was cast unto the earth, he persecuted the woman which brought forth the man child. And to the woman were given two wings of a great eagle, that she might fly into the wilderness, into her place, where she is nourished for a time, and times, and half a time, from the face of the serpent" (Revelation 12.10,13-14 KJV bible). Time, times, and a dividing of time, is another way of saying 1 year, 2 years, and 1/2 a year, otherwise known as 3 and 1/2 years. So the devil is cast out sometime during the 1st half of the seven year tribulation period (7/2 = 3.5), because the persecution takes place during the entire second half.
We can also narrow the time down by saying that Satan is cast out at the third trumpet, because he is the bitter star "wormwood" which pollutes a third of the waters, "And the third angel sounded, and there fell a great star from heaven, burning as it were a lamp, and it fell upon the third part of the rivers...And the name of the star is called Wormwood: and the third part of the waters became wormwood" (Revelation 8.10-11 KJV bible). This is why he is able to release his locust army from the Abyss at the fifth trump (Revelation 9.1-2), because he is already on Earth having been cast out at the third. Suffice to say, that unless you adhere to the belief that the tribulation described in the book of Revelation has already come and gone, then Satan and his angels must still be residing in heaven.
The book of Ephesians informs us on this subject, when it refers to Satan and his angels as dark powers and principalities in the heavenlies, "For our struggle is not against flesh and blood, but against the rulers, against the powers, against the world forces of this darkness, against the spiritual forces of wickedness in the heavenly places" (Ephesians 6.12 NASB bible). Also in Ephesians, Satan is refered to as the prince of the power of the air, "according to the prince of the power of the air, of the spirit that is now working in the sons of disobedience" (Ephesians 2.2 KJV bible). Both of these verses suggest that devil and his angels are still in heaven, and the time of their expulsion has not yet arrived.
Several verses in the New Testament might seem to contradict the idea that Satan and his angels are in heaven, and I will briefly discuss them. Jesus says in Luke 10.18, "I beheld Satan as lightning fall from heaven" (Luke 10.18 KJV bible). This is a spiritual description of the breaking of Satan's power over those people who had received the message of Jesus' apostles, which is the subject of Luke 10. Further, Luke 10 is pre-crucifixion, but we know from Revelation 12 that the devil and his angels are defeated in heaven by the blood of the Lamb, "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" (Revelation 12.11 KJV bible). Thus, the war in heaven along with Satan's expulsion are post-crucifixion, and could not have been occurring during the time of Luke 10.
Two more seemingly contradictory verses come to us from Revelation. First, "And I beheld another beast coming up out of the earth; and he had two horns like a lamb, and he spake as a dragon" (Revelation 13.11 KJV bible). This is undoubtedly Satan, but then why does it describe him as coming up out of the earth, if in reality he will be cast down from heaven? The answer is because it is him in his role as the false prophet or deceiver of nations. He is cast down as the accuser of our brethren (Revelation 12.10), but he rises up as the false prophet. The false prophet will superficially appear like the Lamb or Messiah, but instead of the truth, he will teach the doctrine of the dragon (Revelation 13.11). Lastly, if Satan is in heaven, why is he described as the king of the Abyss in Revelation 9, "They have as king over them, the angel of the abyss; his name in Hebrew is Abaddon, and in the Greek he has the name Apollyon" (Revelation 9.11 NASB bible). The simple answer is that his evil spirit rules in the Abyss, even though he is not down there yet. The Abyss is part of Satan's spiritual dominion, but he is not yet captive to it.
I should also point out that not all of the fallen angels are in heaven. Recall, that both Jude 6 and 2nd Peter 2.4 speak of those angels who left their 1st habitation, and are now bound in Tartarus (a part of Hades), "And the angels which kept not their first estate, but left their own habitation, he hath reserved in everlasting chains under darkness unto the judgment of the great day" (Jude 6 KJV bible). They are currently imprisoned in Tartarus, awaiting the great day of judgment (see also Genesis 6.4).