At this point in Matthew’s narrative, we know two indisputable facts. One, Mary is pregnant, and two, Joseph is not the father of the child. A third crucial fact comes by way of angelic revelation. The child in Mary’s womb was conceived by the Holy Spirit. That means Mary is still a virgin.
But what was the significance of Mary’s pregnancy even though she had not had relations with Joseph or any other man? Joseph likely would have spent some time puzzling over that question if the divine messenger had not immediately clarified his pronouncement with these words, “‘And she will bring forth a Son, and you shall call His name Jesus, for He will save His people from their sins’” (Matthew 1:21).
The angel tells Joseph that Mary will actually bear a son. And not just any son, but Jesus, who “will save His people from their sins.” God chose the name Jesus for His Son because its basic meaning defined the fundamental, overarching purpose for the Son’s coming to earth. Jesus is the Greek form of the Hebrew Joshua, Jeshua, or Jehoshua, each of which means “Jehovah (Yahweh) will save.” The baby Mary had conceived by the power of the Holy Spirit and would give birth to in the plan of God would grow up to testify to the Father’s salvation and would Himself be that salvation. By His own sacrificial death on the Cross and triumphant Resurrection from the grave He would save His own—all those who are drawn from sin to repentance and who receive faith to embrace His atoning work.
Here’s the significance of the virgin birth: Since Jesus was conceived by the agency of the Holy Spirit, God was His Father; His lineage was a holy one. Therefore, Jesus was able to save His people from their sins. That’s the good news of Christmas. Rejoice in it!