The challenging verses at the end of the Psalm can only be read in context of the whole Psalm. The Psalm is a contrast between the rule of God and God’s chosen ruler, and the earthly rulers.
God’s anger and mockery are explicitly named here, in a way that perhaps we don’t think of as normal. God demands a deference from the rules of the earth that seems arrogant. God speaks with a anger, terrifies with fury, and threatens destruction with an anger than can be ignited in an instant.
How is it that we relate to God? How does God relate to us? What happens when our ideas of how this works contracts with Scripture or the narrative of those around us? Is this our God? Is this God speaking or the Psalmist? Is this for that time, or these times?