Luke 11:21 -22 – When a strong man, fully armed, guards his own palace, his goods are safe; but when one stronger than he attacks him and overcomes him, he takes away his armor in which he trusted and divides his spoil.
The above words are those of Jesus after He has been charged with casting out demons by the power of Satan. “Satan does not work against himself” Jesus responds and then he tells the little parable about a strong man guarding a house. The strong man guarding the house is Satan. The house is safe until someone stronger than the strong man comes along and overpowers the guard and runs off with the spoil.
It puts me in mind of this:
The puny god here is Satan himself. Satan does not cast out demons. Satan guards them. He puts them in the houses of the hearts and souls of men so that they are enslaved and useless and damned. He puts people under the influence of evil and keeps them captive to sin and despair and hate and greed and all manner of whatever can keep their attention off their Creator and Saviour. Paul puts it this way:
2 Corinthians 4:4 – In their case the god of this world has blinded the minds of the unbelievers, to keep them from seeing the light of the gospel of the glory of Christ, who is the image of God.
2 Corinthians 4:6 – For God, who said, “Let light shine out of darkness,” has shone in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ.
When you were dead in your sins and in the uncircumcision of your flesh, God made you alive with Christ. He forgave us all our sins, having canceled the charge of our legal indebtedness, which stood against us and condemned us; he has taken it away, nailing it to the cross. And having disarmed the powers and authorities, he made a public spectacle of them, triumphing over them by the cross.
Revelation 7:9-10 – After this I looked, and behold, a great multitude that no one could number, from every nation, from all tribes and peoples and languages, standing before the throne and before the Lamb, clothed in white robes, with palm branches in their hands,  and crying out with a loud voice, “Salvation belongs to our God who sits on the throne, and to the Lamb!”