The Psalmist in the rest of Psalm 96 is telling us that we should tell those who do not know God that He reigns. He established the world and He will judge the people righteously. Knowing that God will not let evil continue forever and instead will bring judgment, the heavens will rejoice. The earth will be glad. The sea will roar in gladness. The fields will be joyful and the woods will rejoice. Truth is in power, are we also rejoicing over that and the power that our Father gives to us as protection?