“I will tell of the decree: The Lord said to me, “You are my Son; today I have begotten you. Ask of me, and I will make the nations your heritage, and the ends of the earth your possession. You shall break them with a rod of iron and dash them in pieces like a potter’s vessel.”” -Psalm 2:7–9
This pericope is expressed in the ceremonious language of coronation, royal inheritance, and dynastic rulership. It refers to the Davidic Covenant, the Judaean Dynasty if you will, inaugurated in the reign of David and fulfilled in the reign of Jesus Christ.
Verse seven is best understood in light of 2 Samuel 7:14. God promises to become a father to the king as the king becomes a son to the father. The divine right to rule is given the king by God himself. Consider the way the Apostle’s interpreted the voice out of Heaven at Jesus’s baptism and transfiguration (Matt. 3:17; 17:5; 2 Pet. 1:17 cf Acts 13:26-39 cf. Hebrews 1:5).
As the only legitimate Son of the Father, Jesus has been given the divine right to rule the nations. He is our rightful King.