When examining the genealogies of Christ as outlined in the Gospels of Luke and Matthew, significant discrepancies arise which have puzzled interpreters since ancient times. The key differences are as follows: 1) In Matthew, Joseph's father is named Jacob (Matthew 1:16), whereas in Luke, he is recorded as Eli (Luke 3:23). 2) Both genealogies list Salathiel and Zerubbabel with different paternal lineages; in Matthew, Salathiel is the son of Jechoniah (Matthew 1:12) while in Luke, he is referred to as the son of Neriah (Luke 3:27). Likewise, Matthew indicates that Zerubbabel is the son of Abiud (Matthew 1:13), while Luke lists him as the son of Risaiah (Luke 3:27). 3) According to Matthew, Joseph is a descendant of David through Solomon (Matthew 1:6-7), while Luke traces his lineage through Nathan (Luke 3:31). 4) The names appearing in both genealogies from David to Salathiel (Matthew 1:7-12; Luke 3:31-27) and from Zerubbabel to Joseph (Matthew 1:13-16; Luke 3:27-23) differ, along with varying total counts of names.
Explanations for these discrepancies include: 1) It is proposed that Matthew presents the lineage of Joseph while Luke provides that of the Virgin Mary, as both descended from David albeit through different lines. However, this interpretation is contradicted by Luke’s explicit mention of Joseph's genealogy (Luke 3:23), and genealogical records typically do not include female lines, even though Mary also stemmed from David's lineage. 2) Another suggestion posits that the individuals in both genealogies are the same but known by different names, reflecting the Jewish custom of assigning multiple names to one person. This theory, however, does not align with the distinct lines traced from David through Solomon and Nathan, nor does it sufficiently address the varying numbers found within the genealogies. 3) A more plausible explanation relates to the law of leverate marriage, wherein the brother or nearest male relative of a deceased man without children would marry the widow to ensure the family line continued (refer to note on Matthew 1:12). Children resulting from this union would have two fathers: one biological and one legal. For instance, Matthew refers to Salathiel as the son (by law) of Jechoniah, the childless man, while Luke names his biological father as Neriah, who reinstated the lineage of Jechoniah.
From Zerubbabel, who was legally considered Salathiel's son, came Abiud and Risaiah. Matthew follows the line of Abiud while Luke follows that of Risaiah. Matthew’s genealogy traces back to David through Solomon, while Luke’s goes through Nathan. In each genealogy, Matthew links to Jacob and Luke to Eli, both recognized as fathers of Joseph. Specifically, Eli, the son of Matthat, died without heirs, and Jacob—his closest relative—through Eli’s widow, continued the lineage, leading to Joseph, who, thus, is the son of Jacob in the physical sense and of Eli in accordance with legal tradition.
This understanding of genealogical disparities can be traced back to Julius Africanus in the second century, who referenced accounts from relatives of the Blessed Virgin (Euseb. Church Hist. 1, 7). This interpretation has garnered acceptance among numerous church fathers and scholars. Such applications of the law of leverate marriage feasibly occurred during periods of duress for the house of David—particularly during the Babylonian Exile and preceding Christ's arrival, when David's bloodline no longer held sovereignty in Jerusalem.