Because God alone is Lord, God does all things that would be regarded as the work of the gods, creating light and darkness, making weal and woe.
This is perhaps the strongest of the several “I am” statements in this part of the book. God says personally and directly who God is, making clear that there is no other God.
This text can be comforting and disturbing. The other gods, who mean Israel ill, are dismissed, leaving only the Lord, the God of the exodus, as the divine power in the life of Israel and the world–good news, indeed! But power is seen both in light and darkness, both in weal and in woe. What does it mean that God is Lord of both? Is this still good news, especially if one translates with KJV: “I make peace, and create evil”?
Isaiah’s primary point remains always good news–there is no other divine power. The ancient gods might well be good or evil spirits, lords of light or lords of darkness. But Israel’s God is One, God alone, and Israel’s God is always the God of The steadfast love (hesed) of God is the assurance of God's loving kindness, faithfulness, and mercy. This assurance rings throughout the Old Testament, and is affirmed more than 120 times in the Psalms. In some hymns of praise the response of the people was likely.... All aspects of life, the good and the bad, are finally in the hands of a loving God.
The text does not imply that everything that happens is God’s will. Isaiah, son of Amoz, who prophesied in Jerusalem, is included among the prophets of the eighth century B.C.E. (along with Amos, Hosea, and Micah)--preachers who boldly proclaimed God's word of judgment against the economic, social, and religious disorders of their time. recognizes that Israel acts contrary to God’s will (for example, 43:27-28) and so do the nations (47:6-7). In this book there are many agents who have real power to do good or ill: Israel, the servant, the prophet, Persian leader who allowed Jewish exiles to return home., Babylon, the nations, and others. But there is only one God, only one who has power in heaven.
This passage ascribes the “darkness” and “woe” that Israel has experienced in its exile to God; it does not mean to say the power of “Evil” itself is God’s Creation, in biblical terms, is the universe as we know or perceive it. Genesis says that in the beginning God created the heavens and the earth. In the book of Revelation (which speaks of end times) the author declares that God created all things and.... To be sure, Israel has brought darkness upon itself by its own sin, but ultimately God has taken charge of that darkness to turn Israel from sin to renewal (40:2).