The righteous and devout end up getting destroyed—or at least, they seem to end up that way.
No one gets what's going on (story of Isaiah, are we right?), but it seems that they've been brought out of calamity and into peace. They're able to attain rest.
But the unrighteous people—the children of a sorceress, or of adulterers and prostitutes—are condemned.
They do things like sacrifice children to their gods and worship idols with wine and grain offerings. Neither of which are really cool with God.
God also furiously notes that they sacrifices to other gods, put up pagan symbols, and generally cheat on God with other idols. He's also pretty upset that they tried to descend to the realm of the dead.
He realizes that they think these sorts of things are working out okay, but God is here to remind them that everything is going to go south, if they keep it up.
God asks the idol-worshipers why they've ignored him for so long. He says he's been lenient towards them by turning away from their transgressions. He even says he'll take their righteous acts into account.
But in the end, it still won't be any good. Their idols will shatter and be blown away like dust. Talk about a poor return on investment.
Nevertheless, everyone who turns to God will have peace. Hint, hint.
God's going to remove the obstacles from his people, letting them all move towards him. He'll have mercy on the humble and penitent people—he won't be furious forever.
The wicked, however, aren't going to have any peace. Their passions make them like a tossing sea that can't be still, throwing up "mire and mud." Pro tip: Don't surf on the sea of the wicked.