The rulerof Tyre said he was a god. It sounds audacious that anyone could say that, but change happens subtly. Just look around.
“Because you regard your heart as that of a god, I am about to bring strangers against you, ruthless men from the nations” (v. 6-7).
Why did they say this? It says “in your pride” they said this. When a nation becomes prosperous, they tend to shift away from the LORD God being at the center and more towards the political powers that be as the central source for direction, morality and governance.
Government is to work with God, not become a god.
But they lost control and the government became center place. They rejected God and thought that they knew better. They thought that they were as a god and had the wisdom of the world.
Because of this the LORD was going to bring against them enemies that were unfortunately known to be ruthless. They would come like waves. And they would die like mere mortals. They would see that they were not gods.
So the LORD brought upon them a lament. Because they would be destroyed and it would be ugly.
As an aside, some say this section is figurative and a typology of the fall of satan. That just like the king of Tyre reveled in his beauty and wealth and became prideful and arrogant, so satan also fell. They say this because “Eden” is mentioned. But “Eden” is also mentioned in Ezek 31 for Egypt which would also fall. The context seems to indicate that this is more just about a judgment of God where God will uses Babylon to instigate the downfall of Tyre for its pride.
Either way, the source of their fall was their pride. Their own wisdom and thinking became the center of their justice, righteousness and morality instead of the justice, righteous and morality that comes from God. Sound familiar?