How much power does Satan currently have over the world?
Satan is currently the god of this world and is in control, but his power is limited. God's checks and balances hold him in check, so Satan can only do so much. He remains under the sovereign God, and his rule is not absolute or total; absolute power belongs to Christ when He sets up His kingdom.
Les explains that Satan is still held in check by God's checks and balances. He is the god of this world and certainly in control, but he can only just do so much because he remains under the sovereign God. During the temptation, Satan claimed the kingdoms were his and offered them to Christ on condition that Christ fall down and worship him. At that point Satan evidently did not understand or comprehend that Christ was going to have those kingdoms. When Christ sets up His kingdom, His power will be absolute, total, and glorious, unlike Satan's limited current rule.