Verses 4-6 of this psalm are God’s declaration concerning Christ. In His ascension Christ was installed, enthroned, as God’s King in the heavens for God’s kingdom to fulfill His economy (Mark 16:19; Acts 2:36; 5:31; Rev. 1:5a). This kingdom includes all the nations as Christ’s inheritance and the limits of the earth as Christ’s possession (v. 8; Matt. 28:18-20). Eventually, in His universal kingdom Christ will rule the nations with an iron rod (v. 9; Rev. 19:15).
This psalm reveals the steps of Christ in God’s economy, beginning from His being anointed in eternity in His divinity (v. 2) and continuing with His resurrection (implying His death also — v. 7; cf. Acts 13:33), His ascension (v. 6), His setting up His universal kingdom (Rev. 11:15) with the nations as His inheritance and the ends of the earth as His possession (v. 8), and His ruling the nations with an iron rod (v. 9).