This is a song of the Kingdom of Jehovah as founded upon and administered in holiness. There are three distinct parts, each ending with practically the same refrain. The first acclaims the King enthroned (vv. Psa 99:1-3). The second affirms the absolute integrity of His administration (vv. Psa 99:4-5). The third declares the constant and faithful guidance of His own representatives (vv. Psa 99:6-9).
In each there is a call to the attitude of response to the fact declared. The enthroned King is to be praised. The governing King is to be exalted and worshipped in submission at His footstool. The guiding King is to be exalted and worshipped in fellowship in His holy hill. Finally, in each case, the underlying reason of the King's position and activity, and also therefore, of the response, is that of His holiness. The throne is established in holiness. The guidance is motivated in holiness.
In the fuller light of the Christian revelation we see the threefold fact in the life of God suggested. The Father enthroned; the Son administering His Kingdom; the Spirit interpreting His will through leaders and circumstances, through pity and through punishment.