What does it mean that Satan is “god of this world”?
One might use an illustration of the tenancy of earth as represented as a lease. This tenancy (stewardship) was given to Adam. His sin allowed tenancy to transfer to Satan.
Satan is able to influence this world through those who are eager to do his will;
John 8:44 Ye are of your father the devil, and the lusts of your
father ye will do. He was a murderer from the beginning, and abode not
in the truth, because there is no truth in him. When he speaketh a
lie, he speaketh of his own: for he is a liar, and the father of it.
Ephesians 2:2 Wherein 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:
2 Timothy 2:25-26 In meekness instructing those that oppose
themselves; if God peradventure will give them repentance to the
acknowledging of the truth; And that they may recover themselves out
of the snare of the devil, who are taken captive by him at his will.
The idea of tenancy is further supported by an image of a scroll or book whereby the tenancy of Satan is to be revoked and full ownership of the earth is restored to God and Satan is to be evicted;
Revelation 5:9 And they sung a new song, saying, Thou art worthy to
take the book, and to open the seals thereof: for thou wast slain, and
hast redeemed us to God by thy blood out of every kindred, and tongue,
and people, and nation;
While Satan rules the earth for now, he does not have ownership rights and must await permission from God before he can act on his desires.
Luke 22:31-32 And the Lord said, Simon, Simon, behold, Satan hath
desired to have you, that he may sift you as wheat: But I have prayed
for thee, that thy faith fail not: and when thou art converted,
strengthen thy brethren.
Job 1:7-11 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. And the LORD said unto Satan,
Hast thou considered my servant Job, that there is none like him in
the earth, a perfect and an upright man, one that feareth God, and
escheweth evil? Then Satan answered the LORD, and said, Doth Job fear
God for nought? Hast not thou made an hedge about him, and about his
house, and about all that he hath on every side? thou hast blessed the
work of his hands, and his substance is increased in the land. But
put forth thine hand now, and touch all that he hath, and he will
curse thee to thy face.
The world as a system could be said to have begun at the Tower of Babel. We know that by the time of Jesus the world is seen as something not godly;
John 15:19 If ye were of the world, the world would love his own: but
because ye are not of the world, but I have chosen you out of the
world, therefore the world hateth you.
Ephesians 6:12 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.
Although Satan is a liar, he may have told us something about his relationship with the world when he was trying to tempt Jesus;
Luke 4:5-6 And the devil, taking him up into an high mountain, shewed
unto him all the kingdoms of the world in a moment of time. And the
devil said unto him, All this power will I give thee, and the glory of
them: for that is delivered unto me; and to whomsoever I will I give
it.
In anticipation of the Kingdom that was to come and that Israel would receive her king;
John 12:31 Now is the judgment of this world: now shall the prince of
this world be cast out.
Much of what is written in Revelation occurs because Jesus is opening the seals of the scroll he has received. This process of opening is the process of judgment coming on the earth. Satan has already been judged. Judgment will be carried out as the scroll is opened by Jesus.
Revelation 12:12 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.
A faithful remnant of Israel will be found, the Kingdom of God will come, and Satan will be thrown out.
Revelation 20:2-3 And he laid hold on the dragon, that old serpent,
which is the Devil, and Satan, and bound him a thousand years, And
cast him into the bottomless pit, and shut him up, and set a seal upon
him, that he should deceive the nations no more, till the thousand
years should be fulfilled: and after that he must be loosed a little
season.