Rav Hirsch translates Psalm 76:8 in the following way: "Thus even now You are the One to be feared; You. And who will stand up in Your sight when one Your wrath will come forth?" In this time, when Hashem is hidden from sight, He is still to be feared. Though we infer His presence from historical and current events, we stand in awe of His power and strength. Assaf then extrapolates from our present fear the immensity of our response when Hashem unleashes His anger. Who will be able to stand in full view of Hashem when He stands and executes His judgment? Assaf calls on us and the nations of the world to prepare ourselves in deed, thought and speech for the day of Hashem’s revelation.