“The Lord is slow to anger but great in power;
the Lord will certainly not allow the wicked to go unpunished.”
Nahum prophesied against Nineveh, capital of the pagan Assyrians. God was concerned with all the peoples of the world. He used them for his purposes, even to punish Israel, but he did not hold them guiltless.
God is the sovereign Lord who reigns over all. He continues to work in the world, though he does not provide us details. But we may know that he works still to promote his purpose to save all peoples.