How could Jesus be descended from the royal line of David if he was born of the Virgin Birth? The first chapter of  Matthew traces Jesus' lineage through his father Joseph back to King David through something like 18 generations. But as we know, Jesus was born through the agency of the Holy Spirit meaning that Joseph did not impregnate his mother, the Virgin Mary. 

How would Jesus have a bloodline back to King David?  Was Mary a cousin (of some degree) to Joseph with similar bloodlines?  If not, what doctrine would cause Jesus to be considered descended from King David?  Or put another way, are there any sources that describe what bloodline Jesus actually had through Mary?
The Old Testament has two distinct methods of claiming kingship. One is by descent from David, and the other is by prophetic or divine appointment. Where did David himself get his kingship? It was by prophetic appointment, through Samuel.

One was applicable to the southern Kingdom of Judah, with its capital in Jerusalem, while the other was applicable to the northern Kingdom of Israel, with its capital in Samaria. The requirement for the throne of Judah was Davidic descendancy. No one was allowed to sit on David’s throne unless he was a member of the house of David. So when there was a conspiracy to do away with the house of David (Isaiah 7:2-6), God warned that any such conspiracy was doomed to failure (Isaiah 8:9-15).

Now, Matthew’s genealogy traces the line of Joseph, the step-father of Jesus. Joseph was a direct descendant of David through Solomon, but also through Jeconiah (see Matthew 1, verses 6-16). Now here, we have a big problem, because Jeremiah 22:24-30 says,


  “As I live,” says the Lord, “though Coniah the son of Jehoiakim, king of Judah, were the signet on My right hand, yet I would pluck you off; and I will give you into the hand of those who seek your life, and into the hand of those whose face you fear—the hand of Nebuchadnezzar king of Babylon and the hand of the Chaldeans. So I will cast you out, and your mother who bore you, into another country where you were not born; and there you shall die. But to the land to which they desire to return, there they shall not return. “Is this man Coniah a despised, broken idol—a vessel in which is no pleasure? Why are they cast out, he and his descendants, and cast into a land which they do not know? O earth, earth, earth, hear the word of the Lord! Thus says the Lord: ‘Write this man down as childless, a man who shall not prosper in his days; for none of his descendants shall prosper, sitting on the throne of David, and ruling anymore in Judah.’ ”


This passage says that no descendant of Jeconiah would have the right to the throne of David. Until Jeremiah, the first requirement for messianic lineage was to be of the house of David. So not only must the Messiah come from the line of David, He must also be apart from Jeconiah. But, as we read in Matthew’s genealogy, Joseph is of the lineage of Jeconiah—meaning, none of his descendants could sit on David’s throne. So then, one must beg the question: how could Jesus be the Messiah, if the Messiah must come from the line of David, but also not be of the line of Jeconiah? 

This is where the Virgin Birth comes into play. Remember, Jesus is not Joseph’s biological son, so the Jeconiah curse doesn’t apply to Him. He is, however, Mary’s biological son per the Virgin Birth. But this still doesn’t explain how Jesus is the descendant of David. To answer this, we must discuss Luke’s genealogy. 

Unlike Matthew, Luke follows strict Jewish procedure and custom in that he omits no names and mentions no women. However, if by Jewish custom one could not mention the name of a woman, but wished to trace her line, how would one do so? He would use the name of her husband (possible Old Testament precedents for this practice are Ezra 2:61 and Nehemiah 7:63). That would raise the second question: if someone studied a genealogy, how would he know whether the genealogy was that of the husband or that of the wife since in either case the husband’s name would be used? The answer is not difficult; the problem lies with the English language.

In English, it is not good grammar to use a definite article (“the”) before a proper name (“the” Matthew, “the” Luke, and “the” Mary). However, it is quite permissible in Greek grammar. In the Greek text of Luke’s genealogy, every single name mentioned has the Greek definite article “the” with one exception: the name of Joseph (Luke 3:23). Someone reading the original would understand by the missing definite article from Joseph’s name that this was not really Joseph’s genealogy, but his wife Mary’s.

Furthermore, although many translations of Luke 3:23 read: “…being supposedly the son of Joseph, the son of Heli…” because of the missing Greek definite article before the name of Joseph, that same verse could be translated as follows: “Being the son (as was supposed) of Joseph the son of Heli…” In other words, the final parenthesis could be expanded so that the verse reads that although Jesus was “supposed” or assumed to be the descendant of Joseph, He was really the descendant of Heli. Heli was the father of Mary. Ultimately, Joseph was Heli’s “son-in-law.”

Next, remember King David had more than one son. One of them was Nathan. None of Nathan's descendants had any "Jeconiah-like" curses. Mary was a descendant of Nathan (Luke 3:23 and verse 31—remember, as explained above, although the English text says “the son of Joseph, the son of Heli…” since the original Greek says Heli is the father-in-law of Joseph, logically, Heli is the biological father of Mary). Now, Jesus is completely safe from the problem of the Jeconiah curse, all while being from the line of David, and of the Tribe of Judah.