Why is Satan called the god of this world?
Satan is called the god of this world because Adam, who was given dominion over creation under God, lost that dominion when he sinned. Satan then picked up that forfeited authority. Scripture makes it clear that Satan is the god of this world, and the world lies in the lap of the wicked one.
Les explains that this goes back to Genesis 1:28, where God blessed Adam and Eve, telling them to be fruitful, multiply, replenish the earth, subdue it, and have dominion. Adam was to rule over creation under God and was literally God's second in command. When Adam sinned, he lost that dominion and dropped the ball. Satan picked it up. From that time on, Scripture makes it abundantly clear that Satan is the god of this world, and another Scripture says the world lies in the lap of the wicked one.