An extremely common criticism leveled at the Bible is the rhetorical question, “Where did Cain get his wife?” The point being that if only Adam & Eve were created, and they only had Cain and Able, then how could Cain have found the wife mentioned in Genesis 4:17?
This question has always stumped me. Not in the sense that I can't answer it but rather why do people even ask it. I've sometimes answered this with a short analogy: I've heard various statistics but one source says that if you start with a single pair of rabbits, you could end up with over 50,000 rabbits at the end of three years! Do you understand how that works? The first pair has babies, then the babies have babies, and so on. It's not rocket science. Well, that same principle works with people – albeit not quite as fast.
The Bible names three children of Adam & Eve. They are Cain, Able, and Seth. However, the Bible is clear that Adam had other, “sons and daughters” (Genesis 5:4). So, in case you still haven't figured it out, Adam & Eve had babies, then their babies had babies with each other. That's how it worked and it was how God intended it.
As people start to think about this, a queasy feeling of taboo starts to set in. If their babies had babies with each other, isn't that incest? If it occurred today, that's how we'd describe it but obviously it wasn't seen the same way then. In his article, Francke describes incest as, “weird and disturbing and more than a little icky.” I believe his view (which I share, by the way) is the product of our Western culture. What we might consider gross, other cultures have embraced. Marrying close relatives – such as sisters, cousins, and nieces – has been practiced around the world for millenia.
Why, then, is incest wrong? It's wrong precisely because the Bible has declared it to be wrong. When God gave the Law to Moses, this thing which had been practiced for thousands of years was commanded to cease. Next you might ask why a practice that God intended, He now would say to stop? I won't pretend that I know exactly why but I do know that God is not arbitrary. I suspect it probably is a matter of health.
In the first few generations after Adam and Eve, marrying a close relative was unavoidable. Many generations later, by the time of Moses, there were enough people in the world that it was no longer necessary to marry anyone closely related to you. Furthermore, the genetic burden each successive generation inherited became worse and worse and marrying a close relative now carried a greater risk of defects in the offspring of incestuous couples. When God gave the Law to Moses, He commanded the practice to cease.
Something similar has happened concerning our diets. When God created Adam and Eve, He told them they could eat any green thing. After the Flood, God told Noah he could also eat meat (likely because the world was not as lush as before the Flood). But when God gave the Law to Moses, it included strict prohibitions against eating certain foods. We have, then, another example of something originally allowed but later commanded to end. So what point is proved by Francke asking this question? Absolutely nothing.
I've always thought it a weak argument to build upon points Jesus didn't make. If it's important that we wash our hands after we sneeze, why didn't Jesus ever tell us to do that?! If it's so important to eat vegetables, why didn't Jesus ever tell us to do that?! It should be obvious that these things are important so the fact that Jesus didn't instruct us about them doesn't prove they're not important. I guess I shouldn't say I've never used a “negative argument” but I still say it's the weaker route.
Now, I don't know everything Jesus said – I only know what is recorded in the Bible. I do know we have no record of Jesus ever having said, “Truly I say to you, you shall read Genesis literally.” Such a statement makes little sense, anyway. I generally do not take things “literally” but I take them in the sense they are intended. Can you imagine having conversations where every word is meant to be literal? How would we interpret expressions like, “scared to death” or “my wife's going to kill me”? So Jesus instructing us to take Genesis “literally” would have probably created more problems than it would solve. Taking the Bible “literally” is a straw man caricature made by critics of conservative Christians.
Instead of looking at what Jesus didn't do, let's look at what He did do. We know that time after time, when confronted by His critics (chiefly, the Pharisees), He often responded with, “Haven't you read...” and would then cite some Old Testament passage applicable to the situation. In those situations, rather than offering some “figurative meaning” of the text, He always relied on the obvious meaning of the passage to make His point.
At the end of the day, though, Jesus did often quote from Genesis. Perhaps His most relevant comment on the subject is found in Mark 10:6-8 where Jesus refers to both Genesis 1 and Genesis 2 in the same comment. He certainly seemed to be referring to Adam & Eve as real people. In Matthew 23:35, Jesus refers to a history of martyrdom beginning with Abel and ending with Zacharias (the latter apparently recently murdered by the Pharisees). In Luke 17:27, He compared the suddenness of His next coming to the Flood of Noah. In all of these cases, and others I could cite, He names these people as though they are real characters in History. How ridiculous would it be to talk about Abel (a fictional character) in the same context as Zacharias (a real person known to the Pharisees) or to compare the Flood of Noah (a fictional event) to the Second Coming (a literal event)?
Perhaps I should turn the question around on Francke. I believe Jesus treated Genesis as real history. If Genesis were not meant to literal, why didn't Jesus instruct us to interpret it figuratively? That “what Jesus didn't do” argument works both ways. The difference is that the Bible repeatedly shows Jesus treating people and events from Genesis as “literal” and never as “figurative.” By continuously referring to the things as history, I believe Jesus was indeed instructing us on the correct way to read Genesis.