BROTHERS and SISTERS, it is God Who commanded light to shine out of darkness, and has enlightened our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ. But we have this treasure in clay jars, so that it may be made clear that this amazing power belongs to God and does not come from us. We are afflicted in every way, but not crushed. We are perplexed, but not driven to despair. We are persecuted, but not forsaken. We are struck down, but not destroyed. We are always carrying in our bodies the death of the Lord Jesus, so that the life of Jesus may also be revealed in our bodies. For while we live, we are always delivered to death for Jesus’ sake, so that the life of Jesus also may be revealed in our mortal flesh. So then death is at work in us, but life in you. And since we have the same spirit of faith, according to what is written, “I believed, and so I spoke” (Psalm 116:10). We believe, and so we speak, because we know that He Who raised the Lord Jesus will raise us also with Jesus, and will bring us with you into His presence. For everything is for your benefit, so that as grace is extended to many, this may also cause thanksgiving to be multiplied to the glory of God.
Saint John Chrysostom gives a brief word on what light God commanded to shine,
And where did God command light to shine out of darkness? In the beginning and in prelude to the Creation. Now He said nothing, but Himself became Light for us. And by shining of this Light we do not see sensible objects, but we see God Himself through Christ.
The Whole Counsel of God Bible study: