"For God is the King of all the earth ... God reigns over the nations" (v7-8). Israel, like most ancient nations, worshipped their "own" God. Yet Israel insisted that their God was King everywhere - not just in Jerusalem. This was thrilling: "O clap your hands, all peoples! Shout to God with the voice of joy!" (v1). The Creator is the God of Abraham, and He is good. He is kind, He is merciful, and He never changes.
God is not King only of our hearts, or our churches. He is King of the earth and universe - everything is His.