This is a very odd claim indeed since the Christian bible insists that Jesus is a "virgin birth" and thus he had no earthly father (e.g. sperm) and thus was not the "seed of David." Royal lineage (and priestly, too) is only passed to children if the mother is Jewish and the father is also Jewish and from a given tribe.
A woman passes "who is Jewish" if she is a Jew, but she does not pass lineage (tribal rights). To be a "seed of David" a person would be of the tribe of Judah, and a descendant of Kings David and Solomon on their FATHER's side.
Needless to say, G-d is not a descendant of David. If Jesus was a "virgin birth" somehow impregnated magically he was not a seed of David.
I've had missionaries say "what if the DNA was Davidic"? In other words, Jesus was still a virgin birth, but somehow G-d used Davidic (male) DNA, just without sperm.
Nope. Doesn't work.
Mary was legally married to Joseph (this is per the Christian bible). Thus if she became pregnant by anyone other than her lawful spouse, Joseph, her child had no tribe. Under Jewish law Mary would have been an adultress if anyone other than Joseph impregnated her.
You see, Biblically-speaking, a man is allowed to have more than one wife. (Rabbinically this is prohibited and it was never considered a good idea), but a woman can only have one husband. If a woman got pregnant by anyone other than her husband then the child you not have a tribal status and the woman would be considered an adultress. See Sh'mot / Exodus 20:13. A woman who has committed adultery becomes forbidden to her husband and her former adulterous lover. (See Talmud Sotah 26b.)
This is still true of Jewish law (halacha) today. If a Jewish woman is married and wants to have a child, but her husband is unable to impregnate her, a non-Jewish sperm donor must be used. Legally a Jew may not marry a non-Jew (it simply is not recognized in Jewish law), thus for the woman to not be guilty of adultery the sperm donor must not be Jewish. Realize that in this scenario the child would be Jewish (because the mother passes "Jewishness"), but the child would not have any tribal status because the father was not Jewish, and tribes only pass if the mother is Jewish and the father is also Jewish and knows a tribe he can pass down to his children).
Luke 1:32 says "The L-rd G-d will give him the throne of David his father." but this is obviously false -- David was not his "father" -- and because Mary was married to Joseph when she became pregnant any father other than Joseph disqualified Jesus from being a "son of David" (aka "seed" of David).
Luke 1:36 states that Mary, a married woman (married to Joseph) was impregnated by the "holy spirit" -- not her husband. This immediately means Jesus was not the "seed" of David no matter what the anonymous author of Luke might have put into the "mouth" of the angel speaking to Mary.
Another huge mistake by the author of Luke is he eliminates Solomon from Jesus' lineage!
The T'nach tells us that the right to David's throne passes only through his son Solomon -- bypassing Solomon the author of Luke chooses David's son Nathan -- thus disqualifying Jesus from any claim to the throne even IF Joseph had been his biological father. Note the chart to the left which is found in UriYosef's article Genealogical Scams and Flimflams.
The T'nach (Jewish bible) makes it clear that the messiah must be descended from King David and King David's son Solomon. Some missionaries will claim that the "promise" that the throne must pass through Solomon is conditional, but this is untrue.
Shmuel Beit / 2 Samuel 7:12-16 – When your days (King David) will be completed and you will lie with your forefathers, then I shall raise up your seed after you, that which will issue from your loins, and I shall establish his kingdom. (13) He shall build a Temple for My sake, and I shall make firm the throne of his kingdom forever.
And then read Divrei Hayamim Alef / 1 Chronicles 22:9-10 – Behold a son will be born to you; he will be a man of peace, and I shall give him peace from all his enemies around about, for Solomon will be his name, and I shall give peace and quiet to Israel in his days. (10) He shall build a House in My Name, and he shall be to Me as a son, and I to him as a Father, and I shall prepare the throne of his kingdom forever.
Luke has Jesus supposedly come through David's son, Nathan, also eliminating Jesus from kingship even if Joseph had been his biological father. Read M'lachim Alef / 1 Kings 8:15-20;Divrei Hayamim Alef / 1 Chronicles 17:11-15, 22:9-10, and 28:3-7. Torah is clear that the messiah must be a physical offspring of both David and Solomon. The Torah specifies that blood rights, such as tribal lineage, are transmitted exclusively from a father to his biological sons. Whenever the Israelites were selected to serve in the army, it was done "according to the house of their father" (Bamidbar / Numbers 1:17 - 18).
What of T'hillim / Psalm 132: 11 -- the supposed "prophecy"? It says "The L-rd has sworn to David in truth, from which He will never turn back, "Of the fruit of your body I shall seat upon your throne." This does say the messiah will come from King David.
The only unfortunate thing for the list maker is that Jesus did not come from King David. Joseph was not his biological father (Joseph supposedly was an descendant of King David), but given the two conflicting lineages given for Joseph they would both disqualify him and any of his children from the throne even IF he had been Jesus' biological father. Luke's lineage, by using Nathan and not Solomon, totally disqualifies Jesus even if Joseph's sperm impregnated Mary.