One thing I love about the study of apologetics is that if I am willing to put in the time and effort to study the Word, the answers to my most nagging questions will eventually be teased out of the text.
Take, for instance, the differences in the genealogies of Christ as recorded by Luke and the apostle Matthew. Now, granted, when lengthy lists of unpronounceable names show up in the Old Testament, my natural reaction is to stifle a yawn and buzz through them with gritted teeth. I may be a theo-geek, but that just about tests the limit. I'll be the first to admit that knowing Samlah from Masrekah was the grandfather of Baal-Hanan frankly doesn't do much for me.
However, if we are talking about Jesus, I sit up and pay attention.
Why does the genealogy of Christ matter so much? For one thing, fulfilment of Messianic prophecy stands or falls on His lineage. If uninterrupted descent from David (who lived about 1000 - 900 B.C.) to Jesus can be proven and verified from more than one source, it goes a long way in refuting skeptics' denial that Christ was the Messiah. For another, several sources documenting an unbroken human lineage in a manuscript as ancient as the Bible would provide yet another argument for it's validity.
Besides providing strong evidence of the Bible's historical validity, the human ancestry of Jesus reveals much about the impartial character of God -- He used all kinds of messed up people in His Son's family tree. Jacob was a deceiver. Rahab was a prostitute AND a Moabite, (as was Ruth), the most cursed of all pagan nations. David committed murder and adultery (and by extension, Bathsheba was an adulteress). His son Solomon turned to paganism and was responsible for the division of the kingdom. Manasseh was one of the most evil kings Judah ever had. There were more than a few bad apples on the family tree of our Savior.
As any student of Scripture has noted, the genealogy listed by Matthew differs from Luke's after David. From Abraham to David (Luke goes all the way back to Adam), they are almost the same, but diverge at David. For years, this question troubled me and seemed to cast doubt on the Bible's inerrancy. With some study, I have found that there are several very good explanations for the apparent discrepancy. Evidently, there was more than one way to trace a genealogy in ancient clan-based societies. One type of genealogy in a royal lineage recorded legal heirs to the throne (which, according to many scholars, is what Mathew used), whereas Luke traces the direct bloodline of Joseph to David.
Several scholars suggest that Matthew follows the line of Joseph (Jesus' legal father through Solomon; see Matt. 1:6-7, 16), while Luke records that of Mary (Jesus' blood relative through Nathan, see Luke 3:31). In Lee Stroble's well-known book, "The Case for Christ", this was one possibility put forth, but I personally do not think it is very likely. For one thing, tracing a genealogy through the mother's side would have been highly unusual (although Judaic heritage was considered to be inherited through the mother). More importantly, both Luke and Matthew explicitly name Joseph, without any reference to Mary. Update: here is a well-researched defense of Luke being Mary's genealogy; I may have to re-think my stance:
Assuming, however, that both Gospel writers were tracing Christ's lineage through Joseph, we come to the intriguing question of why Luke names Joseph's dad Heli, while Matthew 1:16 mentions "Jacob, the father of Joseph". To answer that mystery, we need to dig into a study of biblical genealogies. (Hats off to those guys who edit the study Bibles - they've really done their homework).
“Joseph was clearly the son of Jacob (Matthew 1:16, so this verse [Luke 3:23 - says “son of Heli”] should be understood to mean “son-in-law of Heli.” Thus, the genealogy of Christ in Luke is actually the genealogy of Mary, while Matthew gives that of Joseph. Actually, the word “son” is not in the original, so it would be legitimate to supply either “son” or “son-in-law” in this context. Since Matthew and Luke clearly record much common material, it is certain that neither one could unknowingly incorporate such a flagrant apparent mistake as the wrong genealogy in his record. As it is, however, the two genealogies show that both parents were descendants of David—Joseph through Solomon (Matthew 1:7-15), thus inheriting the legal right to the throne of David, and Mary through Nathan (Luke 3:23-31), her line thus carrying the seed of David, since Solomon’s line had been refused the throne because of Jechoniah’s sin” [Dr. Henry M. Morris, The Defender’s Study Bible, note for Luke 3:23 (Iowa Falls, Iowa: World Publishing, Inc., 1995).].
From the NIV Study Bible's Introduction to 1 Chronicles:
"Analysis of genealogies, both inside and outside the Bible, has disclosed that they serve a variety of functions (with different principles governing the lists), that they vary in form (some being segmented, others linear) and depth (number of generations listed) and that they are often fluid (subject to change).
There are three general areas in which genealogies function: the familial or domestic, the legal-political, and the religious. In the domestic area, an individual's social status, privileges and obligations may be reflected in his placement in the lineage (see 7:14-19); the rights of the firstborn son and the secondary status of the children of concubines are examples from the Bible.....As to form, some genealogical lists trace several lines of descent (segmented genealogies) while others are devoted to a single line (linear genealogies).
Comparison of genealogical lists of the same tribal or family line brings to light some surprising differences. This fluidity of the lists may reflect variation in function. But sometimes changes in the status or relations of social structures are reflected in genealogies by changes in the relationships of names in the genealogy or by the addition of names or segments to a lineage. The most common type of fluidity in Biblical materials is telescoping, the omission of names from a list. Unimportant names are left out in order to relate an individual to a prominent ancestor, or possibly to achieve the desired number of names in the genealogy. Some Biblical genealogies, for example, omit names to achieve multiples of 7: for the period from David to the exile Matthew gives 14 generations (2 times 7), while Luke gives 21 (3 times 7), and the same authors give similar multiples of 7 for the period from the exile to Jesus (Matt. 1:1-17; Luke 3:23-38)."
Additionally, the word "father" is sometimes used more loosely in a genealogy simply to mean "ancestor"; likewise "son of" can also mean simply "descendant".
Matthew's Gospel reflects an apparent fondness for numbers and a concern for systematic arrangement...which shouldn't surprise us; after all, he was a tax-collector by profession! Many of the generations between ancestors were assumed, but not listed, by Matthew, such as the elapsed time between Rahab and David. In Matt. 1:8, he calls Jehoram the "father" of Uzziah, but again, several generations were assumed and "father" clearly means "forefather" here. He may have chosen the number 14 for telescoping his genealogy because it is the numerical value of the name David, although that is not certain. In any case, Matthew's genealogy seems to trace the legal lineage of Christ, as indicated by all the kings listed (beginning with David and Solomon).
This practice of "telescoping" genealogies also helps explain why we don't have to be dogmatic about there only being 4,000 years' worth of generations between Adam and Christ. This is a common argument from the Young Earth Theory proponents, who insist that since the Bible's lineage is recorded without any obvious gaps from Adam to Jesus, that "proves" mankind has been around for only about 6,000 years. Clearly, if Matthew could record a pedigree from the Babylonian exile (626 B.C.) to the birth of Christ (generally set at 6 B.C.) in 14 generations while Luke did it in 21, the history of mankind could easily be recorded with representative names and it could appear to cover only 4,000 years. Nowhere does Scripture claim that the list is exhaustive, and neither should we.
Frankly, it would be interesting to see how the genealogy of Jesus' biological family continued, although it is doubtful the church of the first century would have placed importance on such a record. Obviously we know that Christ Himself did not have human descendants (despite what Dan Brown would have us believe), but He most likely did have quite a few nieces and nephews. Scripture is unequivocally clear that Jospeh and Mary parented other children (mentioned in Luke 8:19, Mark 6:3, 1 Cor. 9:5 and elsewhere), so with four brothers and at least two sisters, Jesus probably had a very large extended family. My guess (and it is purely speculation) is that God, in His sovereignty, did not want anyone to be able to boast or take undue pride in linking his or her pedigree to that of His Son, as Old Testament Israel did in claiming human descent from Abraham. The entire theme of the New Covenant proves that our "adoption as sons" or "being grafted in" (to the tree representing God's family) is based on spiritual, and not biological, heritage.