Mt 1:1 The book of the generation of Jesus Christ, the son of David, the son of Abraham.
Mt 1:20 But while he thought on these things, behold, the angel of the Lord appeared unto him in a dream, saying, Joseph, thou son of David, fear not to take unto thee Mary thy wife: for that which is conceived in her is of the Holy Ghost.
Mt 9:27 And when Jesus departed thence, two blind men followed him, crying, and saying, Thou Son of David, have mercy on us.
Luke 3:23 And Jesus himself began to be about thirty years of age, being (as was supposed) the son of Joseph, which was the son of Heli, . . 38 Which was the son of Enos, which was the son of Seth, which was the son of Adam, which was the son of God.
Why give the geneology of Joseph, then?
Terry,
This established Jesus as the son of David. Matthew nailed it with his lineage and rightly so. The scriptures support this in many examples. All Joseph had to do is accept Jesus as his Son which he did and Jesus would be his son. This is why Jesus was supposed to be the Son of Joseph. Legally he was Joseph’s son and a son of David. This also does not disqualify him from also being the Son of Man as prophets were often called by that designation. There is no smoking gun here. Consider what is written in John Gill’s Expositor
being, as was supposed, the son of Joseph;
who had espoused Mary before she was with child of the Holy Ghost, and afterwards took her to wife, and brought up her son; so that it was not known but that he was the son of Joseph. Whether or no the Jewish notion of the Messiah, the son of Joseph {y} may not take its rise from hence, may be considered: however, Joseph might very rightly be called, as he was supposed to be, the father of Jesus, by a rule which obtains with the Jews {z} that he"that brings up, and not he that begets, is called the father, " or parent; of which they give various instances {a} in Joseph, in Michal, and in Pharaoh’s daughter.
Narkissos,
This is also why Luke could use the name of Joseph in his lineage back to Adam. Joseph of course could also be traced back to Adam if need be. But his lineage through Mary would confirm the humanity of Jesus as Son of Man for those inclined to disagree using sex as an argument. Once again John Gill’d Expositor says:
Which was the son of Eli;
meaning, not that Joseph was the son of Eli; for he was the son of Jacob, according to #Mt 1:16, but Jesus was the son of Eli; and which must be understood, and carried through the whole genealogy, as thus; Jesus the son of Matthat, Jesus the son of Levi, Jesus the son of Melchi, &c. till you come to Jesus the son of Adam, and Jesus the Son of God; though it is true indeed that Joseph was the son of Eli, having married his daughter; Mary was the daughter of Eli: and so the Jews speak of one Mary, the daughter of Eli, by whom they seem to design the mother of our Lord: for they tell {b} us of one,"that saw, ..., "Mary the daughter of Eli" in the shades, hanging by the fibres of her breasts; and there are that say, the gate, or, as elsewhere {c}, the bar of the gate of hell is fixed to her ear."
By the horrible malice, in the words, you may know who is meant: however, this we gain by it, that by their own confession, Mary is the daughter of Eli; which accords with this genealogy of the evangelist, who traces it from Mary, under her husband Joseph; though she is not mentioned, because of a rule with the Jews {d}, that
"the family of the mother is not called a family."
The virgin birth story therefore is not a problem under Jewish Law and custom.
Joseph