“He who sits in the heavens laughs; the Lord holds them in derision.” -Psalm 2:4
Here we have a poetic device called parallelism. Parallelism can function in a few different ways. Sometimes it repeats the same idea in a slightly different way to add clarity. Sometimes it contrasts the first idea with its opposite for emphasis. Sometimes it extends the idea, moving from cause to effect or concept to practical application.
Parallelisms are regular a feature of Hebrew poetry and a delightful way to teach the truth.
The way to read the passage is to understand that “he who sits in the heavens” is “the Lord.”
And his “laugh” is one of “derision,” contempt for those who plot against his authority.
As the city of man rages and plots against the city of God, as they take counsel together to throw off the bonds and cords of their rightful King, the Lord scoffs at their efforts.
And if the Lord is not fearful of their rebellion, what are we worried about?