The first half is almost verbally identical with the promise to Mary in Luke 1:31. It is, perhaps, hypercritical to see anything more than a coincidence when such common terms are used, but it was not unnatural that the communications of the angels to both Mary and Joseph should be purposely clothed in language similar to that used of Sarah (Genesis 17:19), and in measure to that used of Hannah. And she shall bring forth. Is the slight adversative force ( δέ) to be seen in the contrast of the physical birth to the spiritual origin? A Son. In this, at least, thou shalt be able to test the accuracy of my statement. And thou shalt call. Taking the position of his father; the child being thus recognized by all as of David's line (of. Kubel). In Luke Mary is told to give the name, but presumably the formal naming would be by Joseph. His name JESUS (cf. Ecclesiasticus 46:1, "Jesus the son of Nave … who, according to his name, was made great for the saving of the elect of God"). For he shall save; for it is he that shall save (Revised Version), equivalent to "He, and no other, is the expected Saviour." (For αὐτός in this sense of excluding others, cf. especially Colossians 1:16-20.) It may, however, here not be exclusive, but only intensive—he being what he is. The connexion will then be—the name Jesus will answer to the fact, for he himself, in his own Person (1 John 2:2), by virtue of what he is (John 2:24, John 2:25), shall save, etc. Jesus, equivalent to Jeshua (verse 16, note); he shall save, equivalent to Joshi' a. His people. Israel after the flesh (cf. John 1:11; Luke 2:10; contrast John 1:29; John 4:42), for whom deliverance from sins must be the first step to restoration to rightful position, and yet the last stage of result from acceptance of Christ. Comparative salvation from sin, due to acceptance of Christ, must precede that restoration which Joseph then desired, and all true Jews still ardently pray for; full salvation from sin will be the final issue of that restoration. From their sins. With a greater salvation, therefore, than that which Manoah's wife was told that her son should begin to accomplish ( 13:5). Observe that this promise of Christ as Saviour is given to Joseph, who had deeper experience of sin (verse 20, note), while to Mary, who is marked by promptness of personal devotion, is given the promise of Christ as King (Luke 1:32,Luke 1:33). Sate … from( σώσει … ἀπό), not merely "out of" ( ἐκ, John 12:27), but from all attacks of sin considered as coming born without (but see Matthew 6:13, note).
The evidence of prophecy. ("Now all this was done.. God with us.") The Revised Version omits the marks of parenthesis. From a comparison of Matthew 26:56 (and perhaps also Matthew 21:4), this is not the utterance of the evangelist, but of the previous speaker, yet formulated by the evangelist (cf. Weiss). The thought, that is to say, is still part of the angel's encouragement to Joseph; the exact mode of expressing the record of that thought is the evangelist's; so also Tatian's 'Diattess.' (or perhaps only Ephraem's comment upon it; of. Zahn), Quod si dubitas, Isaiam audi.