Psalms 47:7-9

Again he called for praise because the Lord reigns over all nations. He looked ahead in time to see this enthronement. It has not yet taken place, but the psalmist was sure it would happen. The King of the Universe will inevitably rule one day over all, and every knee will bow before Him (Philippians 2:9-11). [Note: See Allen, Rediscovering Prophecy, pp. 217-30.]

As the saints experience discouragement, they can find hope and joy in the fact that, one day, Jesus Christ will subdue all His enemies and rule over all the nations.