"Good news, Abe! I've decided you should have the tip of your penis cut off!" That wacky God; what a cut-up! (This is where I'm supposed to say, "No pun intended," with the express purpose of not caring whether you think I intended it or not, but just making sure you didn't miss it.)
Here's a little personal anecdote my mother told me: when I was born, it was widely believed that circumcision was a very healthy thing to do, and they gave my mother a hard time getting out of the hospital with me without having me circumcised. My mother repeatedly explained to the staff that I would be circumcised, but several days later, according to Jewish custom, at my parents' synagogue. Although apparently they had no legal right to do so, they pretty much threatened not to release her until she signed a release form allowing a doctor to do it right away. Weird stuff. Anti-Semitism, or just ignorance? I don't know.
Anyway, getting to today's passage, God appears to Abram again, and makes another covenant with him. Now I've heard it discussed that this is a separate covenant than the one in chapter 15, and this one is a conditional one. I have to admit I'm not real clear on what the difference is, and while part of it is just me being tired, it's also not super clear in the text. The fact that God doesn't give the land to him in his lifetime is something I've already discussed in recent posts, but I'd say verse eight is particularly confusing as the construct "I will give unto thee, and to thy seed after thee" seems to be clearly specifying the giving of the land to Abraham himself. I don't know what the deal is with that.
Now Abram ("exalted father"), who is renamed Abraham ("father of a multitude") has to do something a bit more challenging than cutting up a few animals; he has to cut off his foreskin, and talk every man living in his house into doing it as well. The SAB questions whether circumcision is necessary, and while looking at some of the New Testament verses on the matter can be confusing out of context, I think there is a fairly unified message concerning it. The main N.T. texts that discuss it at length are Acts 15, in which the early church fathers meet together to discuss the matter of circumcision of gentile converts to Christianity, and a large portion of the book of Romans, particularly chapter four, in which Paul points out that Abram was called righteous over thirteen years before he was circumcised. The upshot is that if you're a Jew and you're going to follow the law of the Jews, then you have to be circumcised. If you're a non-Jew who wants to follow God, you don't have to be circumcised. I don't believe I'm mistaken in my understanding that even Jews believe this. This is the first of many commands in the Bible that are specifically for Jews (although Muslims also circumcise), a subject I'll talk about a lot if I ever make it out of Genesis. Circumcision is to be taken very seriously by the Jews, though, to the point that God says a man who is not circumcised can't be part of the Jewish community, another point I'd have to say is rather odd, since one might assume that, as a Jew, it's really his parents' fault if he's not circumcised.
Sarai's name gets changed to Sarah, which changes the meaning from "princess" to "noblewoman", not a big change. The real point of changing the names was in some way that it was significant in this case to add an "H" to each one, I seem to recall being taught when I was a kid, although I can't remember why; it was something to do with God's spirit being on them in some way. The SAB mentions here that Sarah was Abraham's half-sister, which makes the relationship between them incestuous, yes, but Biblical scholars have pointed out that God never said anything against incest until after the Israelites leave Egypt, probably because with the smaller population in the first few hundred years after the flood, incest would have been harder to avoid.
In changing Sarah's name, God also says that He's going to give Sarah a child, and since she's eighty years old and has never conceived, Abraham laughs. God tells Abraham that the child will be named Isaac, a Hebrew name meaning "he laughs" because, as explained more in the next chapter, everyone is going to laugh at the idea of an 80-year-old woman having a child. (The SAB doesn't put its laughing "absurdity" icon next to verse 16, a place where one might actually consider it respectful to do so!)
So the chapter ends with Abraham circumcising himself, his son Ishmael (Muslims circumcise at age 13, following the tradition of their forefather!), and all of his male servants. While the Bible doesn't say this all happened in one day, it probably did happen in a short time frame, and the SAB is right in painting the rather disturbing picture it does in responding to verse 23. I imagine the announcement; "Hey everyone, I'm giving you the rest of the day off, right after you do just one little thing..." Yikes.
I guess the only thing I haven't covered here is the issue of Ishmael's age, but I think that's really a matter to cover in chapter 21, if indeed it's a matter at all. I don't think it is, but I'll address it when I get there.