So Cyrus, from what we can tell, probably had the idea that even Yahweh, the God of Israel, had really blessed him in his triumph over the Babylonians; and even the Babylonian god Marduk, had given him great favour. So in a real sense, what we see is this man being raised up by God and recognizing the God of Israel. What we see [here] is just [the same] as God hardened Pharaoh's heart—what did the hardening of Pharaoh's heart do? It precipitates the Exodus. [So] we see God hardening the heart of Nebuchadnezzar—what consequence do we see? It precipitates the captivity. So God actually softens and stirs Cyrus' heart. And so Solomon had said a few centuries before
Brian Borgmanthe king's heart is like channels of water in the Lord's hands and he turns it wherever he wills.So God is not only sovereign in fulfilling his Word through the prophet Jeremiah, God is absolutely sovereign over Cyrus. Prophesying two hundred years before he exists, telling exactly what he is going to do, and then it is God himself who stirs up Cyrus, and in a sense softens his heart to do his will.1
1 In the first year of Cyrus king of Persia, that the word of the LORD by the mouth of Jeremiah might be fulfilled, the LORD stirred up the spirit of Cyrus king of Persia, so that he made a proclamation throughout all his kingdom and also put it in writing: