Psalms - Chapter 66
The Messianic Era
This Psalm was composed later in David's life, when he was securely established on the throne and free from the persecutions referred to in many other Psalms. In this Psalm, David focuses on the Messianic era.
David calls upon the nation of Israel to sing to G-d and to sanctify Him in the eyes of the world. G-d's glory is inherent and our praises of Him should reflect that reality. We should proclaim how awe-inspiring the things He created are. G-d is so powerful that when He displays His might (in the form of tsunamis or whatever), even the wicked turn to Him. Eventually (in Messianic times), the whole world will come to recognize G-d and to praise Him.
Go see the incredible things that G-d does for humanity. (According to the Radak, this is what the people of the world will say to one another in Messianic times.) For example, He split the sea when the Jews left Egypt; He performed a similar miracle at the Jordan River when they entered the land of Israel forty years later. G-d rules the world and keeps an eye on all the nations, examining their deeds. The wicked should watch themselves, because He does repay people accordingly for their deeds, even if not immediately.
Let the nations resound with the sound of their praises to G-d! He puts our souls on the proper path, so that we may merit life in the Next World. He tests us in order to refine us, like a silversmith removes impurities from the metal. We have endured many trials under our enemies, but they served to purify us, like fire and water are used to purify vessels and make them kosher. Now, after our exile and oppression, let us rebuild the Temple and offer our sacrifices to G-d.
Let every person who places his trust in G-d pay attention as G-d's deeds are recounted. David says he has called out to G-d and he has glorified Him. If he had any inappropriate thoughts, G-d overlooked them. Instead, G-d listened to David's prayer, so let Him be blessed for His kindness. (In this last portion, David speaks in the first person, but his story is emblematic of the nation's as a whole.)