“Call His Name Jesus” (Matthew 1:21)
The angel tells Joseph to name Mary’s son, which is an act whereby this son is fully accepted as part of Joseph’s family. This is not at all Joseph adopting Mary’s son. This is a son born in Joseph’s household.
But the angel also tells Joseph to give this son a special name, a name that no one in David’s family ever bore. He is to call him “Jesus,” and to do so because “he will save his people from their sins.”
What’s the connection between that name and that mission? Put another way, what are we to think of when we hear this name “Jesus”?
One answer is that “Jesus,” which is the Greek form of the Hebrew “Joshua,” means “YHWH saves.” And so we might think of this name-giving in relation to the promise in, say, Psalm 130:8 that “He [YHWH] himself will redeem Israel from all their sins.”
True enough. That’s something that we might see, though whether Matthew expected his readers to see it is doubtful. After all, Matthew has to translate “Immanuel” for them. He doesn’t expect them to know what that Hebrew word means, and so it’s not likely that he’d expect them to know what “Joshua/Jesus” means either.
Another answer is that Jesus is given that name because we’re to think of him as the new Joshua, who leads his people where Moses could not, right into the Promised Land. And certainly Jesus does lead his followers into the Kingdom. But the connection between that and “saving his people from their sins” is not entirely clear.
But there is a Jesus/Joshua in the Bible who is connected to forgiveness for God’s people. That’s Joshua, son of Jehozadak (Zech 3, 6). To us, he may be an obscure figure because we never read the book of Zechariah. But he wasn’t obscure to Matthew’s readers.
Joshua, son of Jehozadak, is the high priest after the exile, alongside Zerubbabel, the governor, who, though he is from David’s line, is not and cannot ever be the king.
In Zechariah 3, Joshua the high priest represents all of the returned exiles. In the vision, he is wearing unclean clothes and is accused by Satan. How can he draw near to serve YHWH with unclean clothes? That is to say, how can the Jews return to the Promised Land again and draw near to YHWH while their sins have not been dealt with?
But in the vision, the unclean clothes are taken away. The turban is replaced with a new one. And Joshua becomes, in his own person, the promise of forgiveness for the people: “Hear, O Joshua, the high priest, you and your companions who sit before you, for they are a wondrous sign: For behold, I am bringing forth my servant the Branch…. And I will remove the iniquity of that land in one day.”
Then, in Zechariah 6, Zechariah has to crown Joshua the high priest: “Behold the man whose name is the Branch! From his place he will branch out and he will build the temple of YHWH. Yes, he will build the temple of YHWH. He will bear the glory and will sit and rule on his throne. So he will be a priest on his throne and the counsel of peace will be between them both.”
Joshua son of Jehozadak wears the crown for only that day, and then it is placed in the temple as a memorial. But there is coming a day, Zechariah says, when iniquity will be taken away and Joshua/Jesus will be both priest and king.
How would that happen? The answer given in Zechariah 4 applies here, too: “Not by might and not by power, but by my Spirit.”
And the angel tells Joseph that the Spirit has brought about Mary’s pregnancy, that the virgin will conceive and bear a son, and that the son must bear the name of Joshua, son of Jehozadak, because the prophecy in the vision of Zechariah 3 is going to be fulfilled: he will save his people from their sins.
[Most of this I owe to Jakob van Bruggen’s commentary on Matthew. Too bad it’s not in English.]