The time has come,” he said. “The kingdom of God has come near. Repent and believe the good news! – Mark 1:15

The news about the kingdom is that God changed who has his authority.

• Authority = eksousía (from /ek, “out from,” which intensifies /eimí, “to be, being as a right or privilege”) – authority, conferred power; delegated empowerment (“authorization”), operating in a designated jurisdiction. – Bible Hub
• The NIV usually translates eksousía as authority; where they don’t in the verses below, I’ve put it back in

Authority is always legitimate, even if it’s not used properly (a football referee has legitimate authority, even if he’s using it to cheat on games). Authority is different than power (a football player might be powerful, but the coach has the authority to play them or not). Power does not imply legitimate authority, nor does bad behaviour imply that your authority is illegitimate.

God is always sovereign, but he delegates his authority to others throughout history.

• The Most High is sovereign over all kingdoms on earth and gives them to anyone he wishes – Dan 4:17; 4:25; 4:32; 5:21
• For there is no authority except from God, and those that exist have been instituted by God – Ro 13:1
• Jesus answered, “You would have no power [authority] over me if it were not given to you from above. Therefore the one who handed me over to you is guilty of a greater sin.” – John 19:11

For example, authority was given to…

• People: Then God said, “Let us make mankind in our image, in our likeness, so that they may rule” – Gen 1:26
• Angels: The outcry to the Lord against its people is so great that he has sent us to destroy it – Gen 19:13
• Priests: Only you and your sons may serve as priests in connection with everything at the altar and inside the curtain – Nu 18:7
• Sons of God: I said, “You are gods; you are all sons of the Most High.” – Ps 82:6
• Judges: The Lord raised up judges, who saved them out of the hands of these raiders – Judges 2:16
• Prophets: And all Israel from Dan to Beersheba recognized that Samuel was attested as a prophet of the Lord – 1 Sam 3:20
• Kings: Has not the Lord anointed you ruler over his inheritance? – 1 Sam 10:1
• Celestial bodies: the star of your god Rephan – Acts 7:43
• Idols: We should not think that the divine being is like gold or silver or stone—an image made by human design and skill. In the past God overlooked such ignorance, but now he commands all people everywhere to repent. – Acts 17:29-30
• Death: death reigned from the time of Adam to the time of Moses – Ro 5:14
• Sin: so that, just as sin reigned in death – Ro 5:21
• The Law: the law was our guardian until Christ came – Gal 3:24

And to Satan…

• The Lord said to Satan, “Very well, then, everything he has is in your power, but on the man himself do not lay a finger.” – Job 1:12
• I will give you all their [this] authority and [their] splendor; it has been given to me, and I can give it to anyone I want to. – Luke 4:6
• I am sending you to them to open their eyes and turn them from darkness to light, and from the power [authority] of Satan to God – Acts 26:17-18
• For he has rescued us from the dominion [authority] of darkness and brought us into the kingdom of the Son he loves – Col 1:13

But then God fired them all and installed Jesus as King.

• The God of heaven will set up a kingdom that will never be destroyed, nor will it be left to another people. It will crush all those kingdoms and bring them to an end, but it will itself endure forever. – Dan 2:44
• Then Jesus came to them and said, “All authority in heaven and on earth has been given to me.” – Mt 28:18
• He raised Christ from the dead and seated him at his right hand in the heavenly realms, far above all rule and authority, power and dominion – Eph 1:20-21

Jesus’s authority is exercised through us, his body. But it’s no longer delegated from a distance; we only have his authority when we abide in him. This is what Jesus modelled: “Very truly I tell you, the Son can do nothing by himself; he can do only what he sees his Father doing, because whatever the Father does the Son also does.” – John 5:19

• Then the sovereignty, power and greatness of all the kingdoms under heaven will be handed over to the holy people of the Most High – Dan 7:27
• Jesus called his twelve disciples to him and gave them authority to drive out impure spirits – Mt 10:1
• Yet to all who did receive him, to those who believed in his name, he gave the right to become [authority to be] children of God – John 1:12
• “Give me also this ability [authority] so that everyone on whom I lay my hands may receive the Holy Spirit.” – Acts 8:19
• To the one who is victorious and does my will to the end, I will give authority over the nations – Rev 2:26
• The second death has no power [authority] over them, but they will be priests of God and of Christ and will reign with him for a thousand years. – Rev 20:6

In the end, it seems that Satan and his followers will get some authority back:

• They were given power [authority] over a fourth of the earth to kill by sword, famine and plague, and by the wild beasts of the earth – Rev 6:8
• They have power [authority] to shut up the heavens so that it will not rain during the time they are prophesying; and they have power [authority] to turn the waters into blood and to strike the earth with every kind of plague as often as they want. – Rev 11:6
• The dragon gave the beast his power and his throne and great authority. – Rev 13:2
•  It was given power [to them] to wage war against God’s holy people and to conquer them. And it was given authority over every tribe, people, language and nation. – Rev 13:7
• For one hour will receive authority as kings along with the beast – Rev 17:12

And ultimately, God throws them into the lake of fire:

• And the devil, who deceived them, was thrown into the lake of burning sulfur, where the beast and the false prophet had been thrown. – Rev 20:10
• Then death and Hades were thrown into the lake of fire. – Rev 20:14
• Anyone whose name was not found written in the book of life was thrown into the lake of fire. – Rev 20:15