Therefore the Lord will not rejoice in their young men, neither will he have mercy on their fatherless and on their widows; for every one is a hypocrite and an evildoer, and every mouth speaketh folly. For all this his anger is not turned away, and 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 guides of this people mislead [them]; and they that are guided by them are swallowed up.
Isaiah 9:17 Therefore the Lord will not rejoice in their young men, neither will he have mercy on their fatherless and on their widows; for every one is a hypocrite and an evildoer, and every mouth speaketh folly. For all this his anger is not turned away, and his hand is stretched out still.
Isaiah 9:18 For wickedness burneth as a fire: it devoureth briars and thorns, and kindleth in the thickets of the forest, and they go rolling up like a pillar of smoke.
Isaiah 9:19 Through the wrath of Jehovah of hosts is the land burned up, and the people is as fuel for fire: a man spareth not his brother;
The verse centers on "mercy", "therefore", "lord", "rejoice", "young", "neither", "fatherless", and "widows". 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 guides of this people mislead..." into verse 18's "For wickedness burneth as a 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.