My father and my wife both do genealogy. I find it interesting to hear about the various people I'm related to and to learn who I'm descended from in my family tree, but overall, as much as I love history, I don't really get terribly involved in genealogy. Yet one thing remains true in my family tree, from the work both my wife and my father have done: every one of my ancestors has only and exactly two parents. Now, this doesn't mean that I don't have polygamists, divorces, widows, or adoptions in my family tree, I certainly do. Genetically though, all of my ancestors have only two parents, even if we aren't sure who those parents are.
I bring this up because when you look at the genealogy of Jesus, unless there is something seriously missing within the text, you would almost have to wonder how many parents Jesus had and how many parents each of those listed in the genealogies would have had. For instance, Luke 3, in telling the story of Jesus ancestry, lists a different father for Joseph than Matthew 1 lists. From Jesus' grandfather through several generations the lines are different, until we reach Zerubbabel and Shealtiel, then they differ again until we get to David, where they are the same until Abraham. So, unless Jesus had two fathers named Joseph we run into a bit of a genealogical snag when we look at Matthew 1 and Luke 3.
However, what this presents is an opportunity to do further research. One thing I have learned through talking with both my father and my wife is that we often find some tangles in our genealogy. It isn't uncommon to find that one person who thought was the son of another person really wasn't related to him at all. And sometimes you find that what appears to be conflicting information in the genealogy is really just a miscommunication or an error that crept in due to a lack of records.
In the case of Jesus' genealogy we have the records. Both Matthew and Luke provide a record of the family line. So, how do we reconcile the differences?
There are multiple theories offered to resolve the conflict, but before I get to the theories I want to pause to point out the wisdom of the past. What I mean is that we aren't the first generation to read the bible. In fact the bible wasn't originally written in English. People have been reading the bible for thousands of years. And, thousands of years ago, believe it or not, people were having children, and they understood how children came to be and that a child could only have one father and one mother.
My point is: the people who originally put the bible together, the church fathers, knew about the differences between Matthew and Luke. The differences didn't bother them. There was no great conspiracy to clean up the genealogies. And from all the records we have, the differences in genealogy didn't seem to be a major problem for them in taking the bible to be true and accurate.
This alone does not resolve the problem, but it does council us not to think that the problem cannot be answered. Even if we are not happy with the answers we currently have, we have reason to believe that those who originally handed the manuscripts down understood the differences and understood how the passages were reconciled. It is possible that it was something that was so widely understood that there was never any thought given to needing to explain it. Certainly the early opponents of Christianity could have made a big deal about the genealogies, and yet it doesn't appear that this was ever a problem in the earlier history of the church.
So, how do we explain it? If it was something that the early church found easy to explain, shouldn't we understand that today?
Okay, there are two competing theories that I think are the best explanations for what we have going on in Matthew and Luke. First, there is the levirate marriage possibility. In this case the explanation issued is the Matthew is giving the physical ancestry of Jesus and Luke is giving the legal ancestry of Jesus. This would have occurred because Joseph was the legal son of Heli but the physical son of Jacob. It gets somewhat complicated to explain as we don't use the levirate method of marriage today (siblings across America are sighing with relief that they don't have to marry the siblings of their spouses), but, it is an actual possible explanation of the text and would have been a common enough practice in Jesus' time that people would have understood it without confusion.
The second possibility is that Matthew is tracing Jesus lineage through Joseph, but Luke is tracing his genealogy through Mary. Now, the difficulty in this explanation is that the text does not say, "Jesus, son of Mary, daughter of..." Yet, at the same time Luke does say, "Jesus, the son of Joseph, it was thought..." Some scholars take this as a hint that Luke is giving the actual genealogy of Jesus through Mary because he wasn't really the son of Joseph biologically.
To add weight to this view we can also note that in Jesus time it was not uncommon for a son-in-law to simply be called a son. This would be especially true in the case where a man had no sons of his own, so his son-in-law would be his legal heir, or in the case where a son-in-law lived under the roof of his father-in-law. Either could be the case with Joseph and Eli.
In addition, the use of Joseph could be because it was improper to give the genealogy of the mother when noting ancestry. Yet, as Mary was now under Joseph, Luke chose to give her ancestry as a more accurate account of Jesus' origin, and so listed Jesus as son of Joseph and Joseph as son of Eli because this would have been an accurate description of Joseph's relation because of his marriage to Mary. Culturally it would have been very odd to give the genealogy of a woman, but that wouldn't be the only thing odd about the life of Christ.
Remember, the bible had a very high view of women, more so than the surrounding culture during the time it was written. The bible had the women as the first witnesses of Christ's resurrection, which testimony would have been invalid in courts of the day. The bible noted that there were wealthy women who supports Jesus' ministry. The bible also records the names of women in the genealogy of Jesus.
There are other arguments for why Matthew and Luke may be different, but I think these two are the strongest contenders when you examine the evidence. At the end of the day we cannot give an absolute answer, but we can be confident that the question is not without an answer. Yes, believing that this conflict can be resolved takes faith, but if you want to argue about something as minor as Jesus' genealogy lets argue about something that requires real faith: the idea that a man died and rose again from the dead, and that this man was God incarnate, and that sinners are redeemed through his blood.
Is there a reasonable answer as to the differences between Matthew's and Luke's genealogies? Yes, there are in fact at least a couple of reasonable answers. Can I tell you, with certainty, which of those answers is the right answer? No, I can't. But, still we can hold that the bible is absolutely true in all it says, and this question is not the death knell of Christianity.