6 For God, who commanded the light to shine out of darkness, hath shined in our hearts, to give the light of the knowledge of the glory of God in the face of Jesus Christ.
Now he did not observe how much this clause of the sentence made against him: "For God, who commanded the light to shine out of darkness, hath shined in our hearts, to (give) the light of the knowledge (of His glory) in the face of (Jesus) Christ." Now who was it that said; "Let there be light? " And who was it that said to Christ concerning giving light to the world: "I have set Thee as a light to the Gentiles" -to them, that is, "who sit in darkness and in the shadow of death? " (None else, surely, than He), to whom the Spirit in the Psalm answers, in His foresight of the future, saying, "The light of Thy countenance, O Lord, hath been displayed upon us.
Now, if you will examine the words which precede the passage where mention is made of the outward and the inward man, will you not discover the whole truth, both of the dignity and the hope of the flesh? For, when he speaks of the "light which God hath commanded to shine in our hearts, to give the light of the knowledge of the glory of the Lord in the person of Jesus Christ," and says that "we have this treasure in earthen vessels," meaning of course the flesh, which is meant-that the flesh shall be destroyed, because it is "an earthen vessel," deriving its origin from clay; or that it is to be glorified, as being the receptacle of a divine treasure? Now if that true light, which is in the person of Christ, contains in itself life, and that life with its light is committed to the flesh, is that destined to perish which has life entrusted to it? Then, of course, the treasure will perish also; for perishable things are entrusted to things which are themselves perishable, which is like putting new wine into old bottles.
But does anyone deny that the Godhead of the eternal Trinity is to be adored, when the Scriptures also set forth the inexplicable majesty of the divine Trinity, as the apostle says elsewhere: “For the God who commanded the light to shine out of darkness has shined in our hearts, to give the light of the knowledge of the glory of God, in the face of Christ Jesus?” … Who is it, then, who shined that we might know God in the face of Christ Jesus? For he said: “God shined,” that the glory of God might be known in the face of Jesus Christ. Who else do we think but the Spirit who was made manifest? Or who else is it but the Holy Spirit, to whom the power of the Godhead is referred? For those who exclude the Spirit must introduce another to receive with the Father and the Son the glory of the Godhead.
Do you see how Paul shows the glory of Moses flashing with added luster to those who want to see it? It shines in our hearts, he says, just as it shone on the face of Moses. First he reminds them of what was made at the beginning of creation, and then he shows that this renewed creation is greater.
"Seeing it is God that said, Light shall shine out of darkness, who shined in your hearts."
Do you see how again to those who were desirous of seeing that surpassing glory, I mean that of Moses, he shows it flashing with added lustre ? 'As upon the face of Moses, so also has it shined unto your hearts,' he says. And first, he puts them in mind of what was made in the beginning of the Creation, sensible light and darkness sensible, showing that this creation is greater. And where commanded He light to shine out of darkness? In the beginning and in prelude to the Creation; for, says he, "Darkness was upon the face of the deep. And God said, Let there be light, and there was light." Howbeit then indeed He said, "Let it be, and it was:" but now He said nothing, but Himself became Light for us. For he said not, 'has also now commanded,' but "has" Himself "shined." Therefore neither do we see sensible objects by the shining of this Light, but God Himself through Christ. Do you see the invariableness in the Trinity? For of the Spirit, he says, "But we all with unveiled face reflecting in a mirror the glory of the Lord, are transformed into the same image from glory to glory even as from the Lord the Spirit." [2 Corinthians 3:18] And of the Son; "That the light of the glorious Gospel of Christ, Who is the Image of God, should not dawn upon them." [2 Corinthians 4:4] And of the Father; "He that said Light shall shine out of darkness shined in your hearts, to give the light of the knowledge of the glory of God in the face of Christ." For as when he had said, "Of the Gospel of the glory of Christ," he added, "Who is the Image of God," showing that they were deprived of His glory also; So after saying, "the knowledge of God," he added, in the face of Christ,' to show that through Him we know the Father, even as through the Spirit also we are brought unto Him.
Since the divine nature is invisible and always remains so, it is seen for what it is in the humanity of Jesus Christ which shines with divine light and sends out its rays.
We should accordingly worship and glorify him who raised our dust to such state, recounting ceaselessly the holiness of him who mingled our spirit with his Spirit and mixed into our bodies the gift of his grace, causing the fire of his Holy Spirit to burst into flame in us. For “he has shone out in our hearts” which had been submerged in darkness.
When the apostle said, “God, who commanded the light to shine out of the darkness, has shined in our hearts,” he referred to the resurrection. He showed this resurrection to be the exodus from the old state which in the likeness of Sheol incarcerates a person where the light of the gospel will not shine mystically upon him. This breath of life shines through hope in the resurrection. By it the dawning of divine wisdom shines in the heart, so that a person should become new, having nothing of the old.
[AD 220] Tertullian on 2 Corinthians 4:6