The genealogies of Matthew and Luke differ in a number of ways.

Commentators have been long been aware of these differences.  For instance, the 19th-century commentators Jamieson, Fausset and Brown write concerning some of the challenges involved in the genealogies:

‘That there should be difficulty in these genealogies is not surprising, considering,

1. the want of sufficient materials of comparison;

2. the double or triple names given to the same persons;

3. the intermediate names omitted;

4. the name of sons given to those who were only in the direct line of descent, and of brothers to those who were only collaterally related;

5. the Levirate law, by which one is called the son, not of his actual, but of his Levirate father (see Deut 25:5-6; Lk 20:28).

(Numbering added)

For such reasons, JFB say, it is not possible to solve every difficulty.  However, it is clear enough that our Lord ‘sprang out of Judah’ (Heb 7:14), and it would be delightful to any Jewish believer, and concilatory to any unprejudiced Jew, to see the external lines of their nationhood converging on Jesus of Nazareth.

Peter J. Williams notes:

‘Matthew’s genealogy runs from Abraham down to  Jesus in three groups of 14 generations. Luke’s genealogy goes from Jesus all the way back up to Adam, and indeed God before him.  While the two genealogies are similar between Abraham and David, they diverge dramatically between David and the exile, meeting for Shealtiel and Zerubabel, before diverging again and only meeting with Jesus’s legal father, Joseph. Consequently, Joseph is presented as having two different fathers: Jacob in Matthew and Eli in Luke.’

Various explanations for the divergences have been offered.

(1) One (probably Matthew) records the ‘official’ genealogy through Joseph, the other the ‘actual’ genealogy through Mary.  This is the view of Howe and Geisler (When Critics Ask).

In the words of Robert Clifton Robinson:

‘There are two different genealogies for Jesus because one is showing Jesus’ legal right to be Messiah through David (Joseph), the other, Jesus physical right to be Messiah through Mary.’

According to this view, Matthew addresses the interests of his mainly Jewish readers, who needed to know that Jesus was the promised Messiah.  Luke addresses those of his mainly Greek readers, who would be more interested in Jesus as the Perfect Man.

However, there is nothing in the text that would suggest this.  In any case, both trace Jesus’ ancestry through Joseph (Mt 1:16; Lk 3:23).

Counting further against the theory that Luke traces Jesus’ genealogy through Mary is the fact that his genealogy consistently focuses on fathers, and the indication that Mary herself was of the tribe of Aaron, and not Judah (she is described as the ‘kinswoman’ of Elizabeth, who herself is said to be ‘from the daughters of Aaron’, Lk 1:5).

(2) One (probably Matthew) spiritualizes the genealogy rather than following it literally.  According to Mark Edward:

‘The prevailing interpretative theory for how the author of Matthew constructed this genealogy is based on his interest in Jesus as the ‘son of David’, a messianic title going back a century or two before Jesus. He uses David to frame the genealogy (1.1,17), as one of the dividers of the three sets (1.6), and to identify Joseph when the infancy narrative proper begins (1.20). In ancient Hebrew, letters had numerical value, which results in the name ‘David’ (דוד) equating to 14. Artificially creating a genealogy of three sets of fourteen comes from this gematria.’

John Nelson takes a similar line.

(3) The lines of descent cross but are different because one list includes several adoptive lines through levirate marriages (Deut 25:5-10) (NT Background Commentary).

James Bejon writes:

‘Consider the case of Boaz and Ruth. Due to Boaz’s (levirate) marriage to Ruth, Obed’s genealogy could be reckoned in two different ways. Boaz acquired Ruth as his wife in order to ‘perpetuate the name’ of Mahlon (Ruth 4.10), so Obed could legitimately be referred to as ‘a son of Mahlon, the son of Eli-Melech (etc.)’. Biologically, however, Obed was ‘the son of Boaz, the son of Salmon (etc.)’. As a result, Obed’s genealogy could be reckoned in two different ways.’

Bejon adds that a similar situation would be created if someone were adopted:

‘For instance, Mordecai is said to have taken Esther ‘as his daughter’ (Est. 2.7). Consequently, Esther’s ancestry could be traced either through Mordecai the son of Jair (Est. 2.5) or through Esther’s biological father (a different son of Jair).’

Bejon shows how this provides a possible explanation as to why Shealtiel is traced back to David in two different ways.  Matthew records his legal line, whereas Luke records his biological line.

(4) F.F. Bruce (Answers to Questions, p40f) inclines to the view that Matthew’s genealogy gives the line of succession to the throne of David (which did not always correspond to the line of descent from father to son), whereas Luke gives the line of Joseph’s descent from David by another branch of the family.  Machen is quoted:

‘There is nothing at all inherently improbable in such a solution.  When a kingly line becomes extinct, the living member of a collateral line inherits the throne.  So it may well have been in the present case.’

In the words of R.T. France (NBC),

‘probably Luke offers us a ‘physical’ family-tree, while Matthew gives the official throne-succession list (which would not necessarily pass from father to son, but would remain within the family). His concern is with Jesus’ right (through Joseph) to the title ‘King of the Jews’.’

Peter J. Williams stresses that ancient genealogies do not necessarily conform to modern ideas of such things:

‘To us, genealogies record faithfully and accurately our lineage, step-by-step, through the generations, without missing any out.’

Williams continues:

‘The two gospel genealogies make different points. Matthew traces from Abraham through the royal line to Jesus, and strikingly mentions four women who were either non-Israelite (Tamar, Rahab, Ruth) or at least had foreign connections (Uriah’s wife). Among other things this prepares us for the end of the book, which shows the gospel going to all nations.  Luke’s genealogy connects Jesus with the first man and helps us to think of the contrasts between Jesus and Adam (and all other humans generally). It’s a perfect prelude to the temptation narrative in Luke 4:1–13 in which Jesus refuses food in the barren desert in contrast to Adam who took the forbidden fruit in a garden full of other fruit.’

McGrath offers what is perhaps a variation on this theme.  He thinks that it is likely that the difference is due to the ‘curse of Jeconiah recorded in Jer 22:24-30.  This says that

‘no descendant of Jeconiah (sometimes called Coniah or Jehoiachin) will ever sit on the throne of his ancestors. Matthew 1:12 says that Jesus was descended from Jeconiah…That might well have led the author of Luke to provide a different lineage for Jesus.’