What does Psalm 45:5 mean?

The initial motivation for this psalm was the wedding of an earthly king (Psalm 45:1, 9). This includes many compliments and praises, some of which seem like exaggerations for effect (Psalm 45:2–4). However, God promised the line of kings proceeding from David would never end (2 Samuel 7:12–13, 16). That means these words also apply, prophetically, to the ultimate King: the Messiah, Jesus Christ. The following two verses, in fact, will be cited in the New Testament for that very reason (Hebrews 1:8–9).

At His return to earth to vanquish His enemies and establish His kingdom on earth, Jesus will slay His enemies. Revelation 19:15 says, "From his mouth comes a sharp sword with which to strike down the nations, and he will rule them with a rod of iron. He will tread the winepress of the fury of the wrath of God the Almighty." No weapon that is raised against King Jesus will prevail. All the armies of the wicked one, the Devil, are no match for Jesus.

Psalm 2 predicts the marshalling of the Devil's forces in the end time as world armies assemble to battle against God (Revelation 19:19–21; 20:7–15). They intend to usurp the Lord from His throne, but their militaristic scheme only causes the Lord to laugh. Psalm 2:5 describes the Lord as speaking to them in His fury. He tells the raging nations: "As for me, I have set [Jesus] on Zion, my holy hill" (Psalm 2:6).