18 Jesus had no human father. Other men mentioned in the Bible, such as Isaac and John the Baptist, were conceived by the supernatural power of God, but they all had human fathers (Genesis 18:10-14; Luke 1:5-7,11-13,18-19). But Mary, Jesus’ mother, had never slept with a man before Jesus’ birth; she was a virgin. Jesus’ father was the HOLY SPIRIT (see Luke 1:26-35 and comment).
19 In Joseph’s mind, Mary had committed adultery. According to Jewish custom, anyone pledged to be married who was then unfaithful was considered to be an adulterer. Whenever an engagement was broken off, a formal divorce was necessary. Joseph planned to divorce Mary quietly in the presence of two witnesses. He was a merciful and righteous man, and did not want to shame Mary in public.
20 An ANGEL told Joseph in a dream that Mary had not committed adultery with another man, but that the father of her child was the Holy Spirit Himself.
21 The angel told Joseph to name the child Jesus, which is the Greek form of the name Joshua, which means “the Lord saves.” Jesus is the Savior because He saves his people from their sins. He saves them from the punishment of sin, which is eternal death (see John 3:16-17; Romans 6:23 and comments). And He saves them from the power of sin through the working of the Holy Spirit (see Romans 8:1-2 and comment).
22-23 Matthew then quotes from Isaiah the PROPHET to show that Isaiah’s prophecy was fulfilled by the birth of Jesus (Isaiah 7:14). Jesus is also called Immanuel, or “God with us,” because in Jesus God came to earth and dwelt among men. And in Christ, God is with us always (Matthew 28:20).
24-25 Many Christians believe that Mary and Joseph had other children after Jesus. The brothers and sisters of Jesus mentioned in Mark 6:3 and John 7:3-5 are probably children of Mary. However, other Christians believe that Mary remained a virgin. They say that the brothers and sisters mentioned above were sons of Joseph by a previous marriage.
For a further description of Jesus’ birth, see Luke 2:17 and comment.