Psalm 2
This psalm is familiar to students of the New Testament by virtue of its relevance for Christ. However, the passage was a royal psalm in the Old Testament and therefore was used by the Davidic kings. (Other royal psalms are 18, 20–21, 45, 72, 89, 101, 110, 132, 144.) Its contents describe a celebration at the coronation despite opposition by rebellious people in surrounding territories. In a word, the psalmist exhorted the pagan nations to abandon their rebellious plans against the Lord and His anointed king and to submit to the authority of the Son whom God has ordained to rule the nations with a rod of iron.
2:7. The psalmist now spoke of God’s affirmation of the king to show by what right the king rules. The decree refers to the Davidic Covenant in which God declared that He would be Father to the king, and the king would be His son. So when David became king, God described their affiliation as a Father-son relationship. So the expression “son” took on the meaning of a messianic title.