One of the great benefits of reading the REC lectionary is that the arrangers of the readings for the daily office (taken from An Australian Prayer Book 1978) frequently pair readings from the OT and NT that deal with the same subject. In the present case, both passages treat of the fading glory of Moses’ face.
The Vulgate rendered the word “sent forth beams” (Hebrew קָרַן) with cornuta esset. This is not, as some have suggested, a mistranslation, but rather an attempt to stretch Latin idiom to capture the etymology of the Hebrew: the root קרן does mean “horn”, and it appears that the Hebrew verb used here is formed by a metaphor from that noun: horns shoot forth from the head of an animal.
Moses’ shining face made the Israelites afraid to come near him (34:30); the veil thus was an expedient to allow Moses to speak with the people without terrifying them. It is important to note that he removed it whenever he spoke with God (34:34). The veil is thus of a piece with the other symbolism of distance, separation, and fearful holiness by which the OT taught that sin had not yet been dealt with. The people had quailed at the voice of God, and were afraid of the “the mount that might be touched, and that burned with fire, nor unto blackness, and darkness, and tempest” (Hebrews 12:18). The result was that they demanded of Moses, “You speak with us, and we will hear; but let not God speak with us, lest we die” (Exodus 20:19).
With this in mind, we should understand 2 Corinthians 3 to be contrasting the boldness of the Church (πολλῇ παρρησίᾳ χρώμεθα, 3:12) with the reticence and fear of the Sinai covenant which prevented access and approach to God. The “public reading of the Old Covenant” is still attended by a veil that prevents the hearers from access to God. This covenant and its veiling of God are nullified in Christ. (3:14)
Paul makes an argument by analogy in 3:15-16. The pattern of Moses’ behavior in Genesis 34 is quoted: “But whenever he turned to the Lord, the veil is taken away.” This verse is misunderstood by many translators and commentators, who think that it means “whenever an unbelieving Jew converts (“turns to the Lord”), the veil on his heart is taken away.” But Paul is quoting the ipsissima verba of Exodus 34:34 (LXX), and there, as we saw above, it is Moses who is unveiled when speaking to the Lord, but veiled when speaking to the children of Israel.
Moses, you will recall, was distinguished by the fact that he alone spoke with God face to face (Numbers 12:8). Paul is saying that Christians are in the position of Moses himself: their relationship to God is not mediated through the Torah “engraved on stone with letters” (3:7), but is through the Spirit, Who is Himself the Lord, YHWH (3:17). And since we are all in this blessed position of unveiled access to God in Christ, we also do not veil our faces like Moses did.
3:13 states that Moses veiled his face “so that the sons of Israel might not gaze upon the end of what was being nullified” – that is, the Torah covenant, being temporary, did not have an abiding glory. But Christians are being changed into the likeness of Christ, and thus go “from glory to glory.” There is no fading.