What does Isaiah 45:3 mean, “I will give you the treasures of darkness”?
In the context, God is addressing Cyrus, the Persian King whom God calls his anointed. This is an appropriate title for the heathen king for two reasons: Cyrus, as a temporal deliverer of God’s people, and serves as an illustration of Jesus Christ, the eternal Redeemer; and because vassal rulers were anointed by their superior rulers, Cyrus, as one who carried out God’s purposes, could properly be said to be an anointed vassal. Like Jesus Christ, Cyrus’ mission was to deliver and to judge. On the night the Persians captured Babylon some of the men entered on the dry river bed and opened the gates to their armies from the inside.
In God’s purpose for Cyrus, He promised to clear the impediments to his progress and purpose (vs. 2). Then in verse 3, the promise is given that, as Israel’s God, the Lord would give Cyrus possession of the “Treasures of darkness.” This referred to the wealth of the vanquished pagan nations which was customarily concealed in subterranean vaults. Thus, they are called the treasure of darkness, i.e., treasures which came from darkness spiritually and literally. They were also called “the hidden riches of secret places (see Jer. 41:8; 50:37).