Glen Scrivener writes about Psalms 1-2:
"The King is the one who meditates on the Law day and night. And then he is prosperous. Well we already know that from Psalm 1. In v3 we see that the Man becomes a prosperous tree (same word as in Joshua 1). And, as we flick back to Psalm 1, this tree imagery from v3 is often used to describe the promised King of Israel. The promised King is often called things like ‘The Branch’ or the Root or He’s likened to a vine.
When you put all this together you get the picture that the Man of Psalm 1 is in fact the King of Psalm 2. The Man of Psalm 1 is the Anointed One (or Messiah or Christ, it’s all the same word) from Psalm 2:2. The Man is the Christ, the Son of God. So you see in both Psalm 1 and Psalm 2 you have a contrast – not between one group of good guys and another group of bad guys. In both Psalms you have one man, the King, who is God’s Righteous, Anointed, Blessed, Beloved Son and then you have the wicked, the other kings of the earth, the sinners, the mockers, the rebels.
And the message of these Psalms is not ‘Don’t belong to the bad guys, belong to the good guys.’ The message of these Psalms is ‘Don’t belong to the wicked, belong to the Blessed Man.’ Belong to Christ, the Son of God. See, take the beginning and end of these two Psalms together and you get the whole message of the Bible in a nutshell. Psalm 1:1 ‘Blessed is the Man’ and Psalm 2:12 ‘Blessed are all those who take refuge in Him.’ That’s the gospel right there. Blessed is the Man and blessed are all those who take refuge in Him. Christ is the One Blessed Man, but He doesn’t keep His blessedness to Himself. It’s a blessing that’s available for all who come to Him."
And here's five mins on the same lines (not by Glen): Psalms are Christian: