Therefore the LORD shall have no joy in their young men, neither shall have mercy on their fatherless and widows: for every one is an hypocrite and an evildoer, and every mouth speaketh folly. For all this his anger is not turned away, but his hand is stretched out still.
Isaiah 9:15 The ancient and honourable, he is the head; and the prophet that teacheth lies, he is the tail.
Isaiah 9:16 For the leaders of this people cause them to err; and they that are led of them are destroyed.
Isaiah 9:17 Therefore the LORD shall have no joy in their young men, neither shall have mercy on their fatherless and widows: for every one is an hypocrite and an evildoer, and every mouth speaketh folly. For all this his anger is not turned away, but his hand is stretched out still.
Isaiah 9:18 For wickedness burneth as the fire: it shall devour the briers and thorns, and shall kindle in the thickets of the forest, and they shall mount up like the lifting up of smoke.
Isaiah 9:19 Through the wrath of the LORD of hosts is the land darkened, and the people shall be as the fuel of the fire: no man shall spare his brother.
The verse centers on "mercy", "therefore", "lord", "shall", "young", "neither", and "fatherless". It is saying that the verse draws attention to "mercy" and "therefore", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 16's "For the leaders of this people cause..." into verse 18's "For wickedness burneth as the fire it...", so "mercy" and "therefore" belong inside that flow. In Isaiah context, the local focus is the Holy One of Israel, judgment and restoration, the servant of the LORD, and Zion's hope.
A plain takeaway is to answer the verse's own emphasis on "mercy" and "therefore" with trust shaped by these words, not by a vague optimism outside the passage.