Luke 1:31

“And behold thou shalt conceive in thy womb,.... Though a pure virgin, which never knew a man; and therefore, "a behold", is prefixed to it, as being what was extraordinary and wonderful; as it is also, in the prophesy of it, in Isa 7:14 to which the angel manifestly refers, and is, by Matthew cited, as accomplished hereby; see Gill on Mat 1:22, Mat 1:23. and bring forth a Son, and shalt call his name Jesus; which signifies a "Saviour"; and a Saviour Christ is of God's appointing, providing and sending; and a very suitable one, being a spiritual Saviour, and a complete one, both able and willing to save to the uttermost all that believe in him; nor is there any other, nor salvation in any other: he is the Saviour of his people, whom the Father has given him, even of all the elect, whether of Jews or Gentiles; and of them from all their sins, and from all their enemies; and whom he saves with a spiritual and eternal salvation.”

“It may perhaps in the first instance of reflection, appear shocking to our ideas, that a God should dwell in a human body; but does not the sun emit its rays into all kinds of places, without any detriment to its purity? How much more would the Sun of justice, assuming a most pure body, formed of the purest blood of the spotless Virgin, not only remain free from every the least stain himself, but even impart additional sanctity to his virgin Mother. (St. Thomas Aquinas)”