The fact the Cyrus mentions the Lord is because he knew that the Lord was the God of Israel. Cyrus did not worship the Lord; he was a pagan. Cyrus also did not truly believe that the Lord was the only God who reigns in heaven. He was most likely a follower of the Zoroastrian religion in which the greatest god is known as Ahura Mazda and all other gods (e.g., Marduk) would be recognized by the Persians as members of Ahura Mazda’s heavenly army of the forces of light. Cyrus thus thought that the Lord was just another god, a member of Ahura Mazda’s army. However, we know what Cyrus did not know. He thought he was just acknowledging the Lord’s existence as one of several gods in the heavenly army, but we know that the Lord is in fact the only true God.
2 “Thus says Cyrus king of Persia: The LORD, the God of heaven, has given me all the kingdoms of the earth, and he has charged me to build him a house at Jerusalem, which is in Judah.