Isaiah 9:18, commentary and pictures

Isaiah 9 belongs to reproofs for great sins committed in Isaiah's time. The prophecy speaks of future events as though they had already happened, using the present tense for the announcement of the Messiah's birth. Its messianic message was misconstrued to expect a famous and powerful Messiah who would lead a successful revolt against Roman rule instead of recognizing Christ.

The verse stands among prophecies of blessing for Israel and the Gentiles that were conditional on the Jewish nation believing Christ and obeying the gospel, so the promised restoration of the kingdom to Israel depended on that obedience and was not owed after Christ was rejected. The thickets of the forest picture the supremacy of Gentile rule, meaning the high places of the forest are Gentile powers set over Israel after Israel's government and kingdom are uprooted and abolished. The verse pictures wickedness burning as fire that devours briers and thorns, kindles in the thickets of the forest, and mounts up like the lifting up of smoke.

The spreading fire shows how sin brings destruction. The verse teaches that the wicked will be punished by fire. That fiery destruction will take place at the consummation of all things, of which the destruction of Jerusalem was a type. The conditions rebuked in Isaiah's time point forward to similar conditions in the last days and to deliverance at Christ's coming. Wickedness is a consuming fire fueled by sin, which scorches rather than warms unless the fuel is removed or its heat is allayed by penitential tears.