Christs genealogy differs in two of the gospels. Which one is the correct one?
This refers to the two different descriptions of Jesus genealogy in Mt 1:1-17 and Lk 3:23-38. The genealogy in the gospel of Matthew is restricted to the Israeli ancestry of Jesus, although in V 3,5,6 it also points out non-Israeli influences from the side of the women. It is shaped by the intention to link Jesus with the two main bearers of the messianic promises, Abraham and David and with David’s line, 2 Sam 7.1+; Isa 7.14f. The genealogy in Luke goes back to Adam, the head of all mankind, and thus gains a more universal character than the one in Matthew. As a descendant of Adam and like Adam without an earthly father (1.35), Jesus establishes a new mankind; maybe Luke is thinking of the new Adam, c.f. Rom 5.12f. From David to Joseph only two names appear in both lists. The discrepancies can be explained by the fact that the legal lineage (law of the levirate, Dtn 25.5+) was equal to the natural lineage. In Matthew, the systematic character of the genealogy is emphasized by the division of Jesus ancestors into three groups of two times seven names, c.f. 6.9f; this format necessitates the omission of three kings between Jehoram and Uzziah and the double counting of Jaconiah, V11-12, (this one name, Jechonias in Greek, can be the translation of two similar sounding Hebrew names, Jehoiakim and Jehoiachin). Both lists end with Joseph, who is only the legal father of Jesus. According to the understanding in those times, the legal parentage alone (through adoption, levirate etc.) conferred hereditary rights, in this case those of the messianic family. This does not exclude the possibility that Mary, too, belongs to this lineage, but this is not mentioned by the evangelists.