Please explain Revelation 12:7-9 [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.
See All...? I see that Satan deceives the world. How can Satan deceive the whole world, if he is/was in heaven?

If we will not be able to escape the evils of war even in heaven, then what kind of heaven is heaven? It is no better than earth. I think this question can be clearly answered if we build on the foundation of the word of God.

First of all, it is important to understand that there are three heavens in scripture (not seven as is traditionally taught by some). When Paul went into the presence of God, he was "caught up to the third heaven" (2 Corinthians 12:2I knew a man in Christ above fourteen years ago, (whether in the body, I cannot tell; or whether out of the body, I cannot tell: God knoweth;) such an one caught up to the third heaven.
See All...). So where are the other two heavens? I have dealt with this in more detail in other places, so I will be brief here. The first heaven is the atmospheric heaven where the birds fly. It is called the "open firmament of heaven" (Genesis 1:20And God said, Let the waters bring forth abundantly the moving creature that hath life, and fowl that may fly above the earth in the open firmament of heaven.
See All...). The second heaven is the starry heaven; what we think of as outer space. It is scripturally called the "firmament of the heaven" (Genesis 1:14-18 [14] And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years: [15] And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so. [16] And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also. [17] And God set them in the firmament of the heaven to give light upon the earth, [18] And to rule over the day and over the night, and to divide the light from the darkness: and God saw that it was good.
See All...) and it is where God placed the sun, moon, and stars. The third heaven then is the abode of God. When God creates "new heavens and a new earth, wherein dwelleth righteousness" (2 Peter 3:13Nevertheless we, according to his promise, look for new heavens and a new earth, wherein dwelleth righteousness.
See All...), He is referring to the first two heavens. Righteousness already dwells in the third heaven and it will not need to be recreated. When heaven and earth flee away in Revelation 20:11And I saw a great white throne, and him that sat on it, from whose face the earth and the heaven fled away; and there was found no place for them.
See All..., God's great white throne (a part of the third heaven) continues to stand.

So now that we have established the existence of three heavens, we need to establish the abode of Satan and his angels. In Ephesians 2:2Wherein in time past ye walked according to the course of this world, according to the prince of the power of the air, the spirit that now worketh in the children of disobedience:
See All..., Satan is called "the prince of the power of the air." If we think of air as oxygen and other gases, this would limit him to the atmospheric heaven. However, if the word air here refers to open space (as I think it does), it would put him in the first and the second heaven. Ephesians 6:12For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.
See All... warns us, "For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places." The high places are certainly those places of Satan's abode above the earth. Isaiah 14:12-14 [12] How art thou fallen from heaven, O Lucifer, son of the morning! how art thou cut down to the ground, which didst weaken the nations! [13] For thou hast said in thine heart, I will ascend into heaven, I will exalt my throne above the stars of God: I will sit also upon the mount of the congregation, in the sides of the north: [14] I will ascend above the heights of the clouds; I will be like the most High.
See All... describes Lucifer as attempting to ascend above the heights of the clouds into heaven. Evidently, he wants his abode to be as high as possible in order to imitate God. Though there is no definitive verse that I know of, the devil may very well have his abode as high in the second heaven as possible at the door of God's third heaven.

Now, we need to look at the context of Revelation 12:7And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels,
See All... to see if we can define the heaven in which this battle is fought. If the battle were to be fought in God's presence--the third heaven; where would Satan be when he was cast out? He would be in the lower heavens. But what does the passage say? Let me piece together some phrases from Revelation 12:7-9 [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.
See All...: "And there was war in heaven... neither was their place found any more in heaven... he was cast out into the earth, and his angels were cast out with him." We can see from this that the devil and his angels were cast out of heaven into the earth. This would indicate that the battle took place somewhere in the first two heavens and not in the third heaven where the presence of God dwells.

In conclusion, I believe that the war in heaven between the devil and his angels and Michael and the Lord's angels is not in the highest heaven but in a lower one. The third heaven where the presence of God dwells is secure and will endure forever as His holy habitation.