How did Luke "sneak in" Mary's genealogy in his gospel when others were based on the descendants of a male? How did an error in Luke's listing of the descendants of Jesus through Mary show up? How is the Lord's identity defined by his relationship as a Son?
Genealogy Comparisons
How do the genealogies of Jesus found in both the gospels of Matthew (Matthew 1) and Luke (Luke 3) compare?
Matthew's genealogy traces the legal lineage of Jesus starting with Abraham, then through the kings of Judah, then through a line of royal descendants to Joseph. Luke, however, traces the Lord's bloodline from Mary all the way back to Adam! Luke is able to do this by employing a little trick.
And Jesus Himself began to be about thirty years old, being, as was supposed, the son of Joseph, the son-in-law of Eli (Heli) . . . (Luke 3:23, HBFV).
Luke uses the phrase "as was supposed the son of Joseph" as a placeholder for Mary. This was done, in part, because accepted genealogies were male-centered for a variety of reasons (inheritance, etc.). We know Luke is referencing Mary and her father as Matthew states that Joseph's father was named Jacob (Matthew 1:16) and not Heli.
Luke's genealogy through Mary proves that Jesus was a Jew as it is the mother, not the father, who determines whether someone is Jewish or not. Why is this important? It is because prophecy states that the Messiah must be a Jew and a physical descendent of King David (Genesis 49:10, Isaiah 9:6 - 7, etc.).
Concerning His Son: Who came from the seed of David according to the flesh . . . (Romans 1:3, HBFV).
Together, Matthew's and Luke's genealogies prove that Jesus has both a legal right to sit on David's throne and that he qualifies through blood to be the Messiah.
Matthew lists 42 names (41 of which are unique) in a symmetrical list of three sets of fourteen. Luke, however, only records a simple list of 76 names.
Matthew's list of Jesus' royal lineage does not mention four of the kings of Judah (Ahaziah, Joash, Amaziah and Jehoiakim) while Luke's genealogical listing through Mary seems to be far more complete.
Luke traces Jesus' lineage back through a man named Nathan to King David (Luke 3:31). Matthew traces it to David through King Solomon (Matthew 1:6). Both Solomon and Nathan were sons of the king through Bathsheba.
David had five sons with the first one, unnamed, dying when he was only seven days old (2Samuel 12:18). Solomon was David's second son and Nathan (likely) his third (1Chronicles 3:5).
The Oldest Prophecy
The oldest prophecy in the Bible is surprisingly based on genealogy!
And I will put enmity (hostility, hatred) between you and the woman, and between your seed and her Seed: He will bruise your head, and you shall bruise His heel (Genesis 3:15, HBFV).
The phrase "her Seed" hints at a Savior who will miraculously come into the world through a means that is impossible for humans to achieve (a virgin birth). Luke's physical genealogy of Jesus, through Mary, shows how God made "her Seed" possible and offers the foundation through which the rest of the prophecy can be fulfilled!
Luke Copies an Error
Which was the son of Saruch (Serug), which was the son of Ragau (Reu), which was the son of Phalec (Peleg), which was the son of Heber (Eber), which was the son of Sala (Salah), Which was the son of Cainan, which was the son of Arphaxad . . . (Luke 3:35 - 36, KJV).
Luke 3:36's part of Jesus' genealogy through Mary states Sala (Salah) was the son of Cainan who was, in turn, the son of Arphaxad. The problem is the Old Testament states that Salah, not Cainan, was the son of Arphaxad (Genesis 11:12). The phrase "Which was the son of Cainan" is incorrect and doesn't belong in the text.
How did this genealogical error creep into the Bible?
Luke almost certainly copied his genealogy of Jesus through Mary from the Septuagint which has the same error. The Septuagint is a Greek-based translation of the Old Testament text written by Jewish scholars in the middle to late part of the third century B.C. The phrase regarding Cainan in Luke 3:36 was erroneously inserted by these scholars.
"Sala is said to be the son of Cainan, and he the son of Arphaxad, whereas Sala was the son of Arphaxad (Genesis 10:24, 11:12), and there is no such man as Cainan found there.
"But, as to that, it is sufficient to say that the Seventy Interpreters (of the Septuagint), who, before our Savior's time, translated the Old Testament into Greek, for reasons best known to themselves inserted that Cainan: and St. Luke, writing among the Hellenist Jews, was obliged to make use of that translation, and therefore to take it as he found it." (Matthew Henry's Bible Commentary).
Luke's use of the Septuagint makes sense as He was a Greek (Gentile) convert to Christianity. He wrote his gospel, with a Grecian audience in mind, for a fellow Greek convert named Theophilus (Luke 1:3).
Who Was Jesus?
Three of the most important descriptors used for Jesus center around his genealogical relationship, as a Son, with King David, God the Father, and mankind in general.
The phrase "son of David" is found sixteen times in sixteen King James New Testament verses. Fourteen of these occurrences are linked to Jesus Christ.
The phrase "son of God" is recorded 47 times in 46 KJV New Testament verses. All of these occurrences are linked directly to Jesus.
The phrase "son of Man" is written 89 times in 85 King James New Testament Bible verses. All of these are in reference to Christ. The overwhelming majority of these were spoken by Jesus or were reported as being spoken by him.
Jesus, as both the Son of God (and man's Creator) and the Son of Man, is the perfect Mediator between the Father and humanity (Hebrews 2:9 - 10, 17 - 18). Luke's genealogy of Jesus, through Mary, unites both the human and divine in Christ.