Zechariah goes in to burn incense, just as Aaron had been instructed to do (Exodus 30:7).
Aaron and later high priests would use incense on the day of atonement: Leviticus 16.11 “Aaron shall present the bull as a sin offering for himself, and shall make atonement for himself and for his house. He shall kill the bull as a sin offering for himself. 12 And he shall take a censer full of coals of fire from the altar before the Lord, and two handfuls of sweet incense beaten small, and he shall bring it inside the veil 13 and put the incense on the fire before the Lord, that the cloud of the incense may cover the mercy seat that is over the testimony, so that he does not die. 14 And he shall take some of the blood of the bull and sprinkle it with his finger on the front of the mercy seat on the east side, and in front of the mercy seat he shall sprinkle some of the blood with his finger seven times.”
Zechariah here doesn’t carry out the blood offering on the day of atonement, but is only making the daily offering of burning incense. From Christian tradition, we think of incense as being symbolic of our prayers rising up to God, as well as marking off sacred space that gives us a sense of stepping out of the mundane. For the high priest, incense also had the protective function mentioned above as well. The smoke from the aroma that makes us aware of the presence of God protects the priest from that awe-ful presence at the mercy seat. It brings us close, and yet serves as a veil of protection.
Calvin writes that such is the function of the cherubim - whose outstretched wings comprised the mercy seat - on the ark: For what, pray, did these figures mean, if not that images are unfit to represent the mysteries of God, since they were so formed as to cover the mercy-seat with their wings, thereby concealing the view of God, not only from the eye, but from every human sense, and curbing presumption? To this we may add, that the prophets depict the Seraphim, who are exhibited to us in vision, as having their faces veiled; thus intimating, that the refulgence of the divine glory is so great, that even the angels cannot gaze upon it directly, while the minute beams which sparkle in the face of angels are shrouded from our view. (Institutes 1.11.3)
Such is our experience with the holy God. Moses encounters Yahweh at the burning bush. He comes closer, but must remove his shoes. He learns God’s name, the disclosure of which promotes intimacy, but the meaning of which conveys deep mystery and otherness - ultimate being. Moses sees the ‘back’ of God, and then must veil his own face for the people’s sake.
At a Christmas party for my work the other night, I had a discussion with one of my Hebrew professors from seminary. Out of three OT profs, he was against speaking the name ‘Yahweh’. I asked him about this, remarking that I and many other young pastors (though not all!) use the name Yahweh in preaching more as a means of getting back to the Hebrew roots and employing biblical theology, all the while getting away from the connotations of overused language in Christian circles. The holy God who revealed himself as Yahweh is the God of us today who calls us to both know and fear him.
My prof gave two reasons why we ought not to do so: first, the Masoretic text doesn’t have it, so we’re putting a word in that’s not there; second, uttering the name treats God solely as dad and friend, but not the holy God whom we fear.
I do use the name in preaching and teaching instead of the LORD, saying it out of respect and accuracy, but also because of the torn veil. I have found that when we introduce our hearers to the God Yahweh, they meet the individual who is both the tribal God of Abraham, Isaac, Jacob, Moses, and the people of Israel, while at the same time is the God beyond all creation and comprehension.
I believe we can have that balance of intimacy/relationship and reverence in employing use of the name.