This appears to be a psalm celebrating the entrance of the Ark of the Covenant into Jerusalem. This psalm glories in God's creation and his rule over it. David also reminds us of God's covenant and the fact he comes down and lives within us ( Holy Spirit) and among us (Christ). The Gospel is proof of this covenant in that God was among us, was one of us and still in his humanity rules over all creation! He is the King of Glory!
Of David. A psalm.
1 The earth is the Lord’s, and everything in it, the world, and all who live in it; 2 for he founded it on the seas and established it on the waters.
3 Who may ascend the mountain of the Lord? Who may stand in his holy place? 4 The one who has clean hands and a pure heart, who does not trust in an idol or swear by a false god.[a]
7 Lift up your heads, you gates; be lifted up, you ancient doors, that the King of glory may come in. 8 Who is this King of glory? The Lord strong and mighty, the Lord mighty in battle. 9 Lift up your heads, you gates; lift them up, you ancient doors, that the King of glory may come in. 10 Who is he, this King of glory? The Lord Almighty— he is the King of glory.