Summary: God peruses people to not stumble in darkness, but come by faith in Him, to everlasting light.
Joy comes with the dawning of the light. But the light would not dawn on the generation of Isaiah’s day. It would come in the future. Before the light would shine, both Israel and Judah would experience the judgment of God for their unbelief and rebellion. Assyria would devour and assimilate Israel; Babylon would carry Judah away captive as a prize of war. God’s people would be devastated, but a remnant would remain and return. When the light dawned, God’s people would include not only those of Jewish heritage and culture but believers from all nations (Braun, J. A. (2000). Isaiah 1-39. The People's Bible (124). Milwaukee, Wis.: Northwestern Pub. House.).
In 733 B.C., Tiglath-pileser III besieged Damascus, invaded the region of Galilee, including Zebulun and Naphtali, and incorporated it into his kingdom (2 Kings 15:29) in fulfillment of God’s Word. “Gloom” and “distress” result from oppression and separation from Yahweh’s covenantal love. But the Lord will graciously turn humiliation into glory. How? By the coming of the Messiah of David (9:1–7). Although the northern tribes had rejected David’s dynasty in favor of Jeroboam (1 Kings 12:1–20), their salvation will come from the very one whom they rejected. The new era will be characterized by great joy. The Messiah will free his people from their enemies and bring the actualization of the Davidic ideal (Elwell, W. A. (1996). Vol. 3: Evangelical commentary on the Bible. Baker reference library (Is 9:1). Grand Rapids, Mich.: Baker Book House.).
In verse 2, following the lead of the previous verse, explains why there will be no gloom where in fact the darkness had been absolute. With the suddenness of dawn (cf. 60:1) comes the announcement that light has appeared to these people. They did not produce it nor are they responsible for it. Where they had been groping in darkness, or sitting in the land of death’s shadow, they suddenly find themselves blinking in the light. Throughout the Bible, God’s presence is equated with light (42:16; 2 Sam. 22:29; Job 29:3; Ps. 139:11, 12; 1 John 1:5). So here, there is light for these people because their sin and rebellion are not enough to keep God from manifesting himself to them. True, they could not continue to choose their sin and have the light, but if they wished to be freed from their sin, nothing could prevent God’s light from shining, as it, in fact, has in Jesus.
All these events are manifestly in the future from the prophet’s point of view, yet the verbs are all in the perfect tense. Apparently these are prophetic perfects. Isaiah has a point of view different from the normal one. In the uncertainty of his own milieu he nonetheless can look at a future moment and describe its events with the certainty of completed actions. No medium or spiritist could do that. The spirits could not explain the origins of the earth, much less the end of it (cf. 41:21–24). But God could give that kind of insight to his prophet.