 Galatians 4 is indeed dense and initially unclear, but that doesn't mask the fact that Paul is making sharp contrasts, those between two women, two covenants, and two mountains. Of course, the passage 421-51 is a tour de force. Paul frames it with Genesis 16-21 in mind. He starts in verse 22 with a simple summary, and he ends in verse 31 with a simple conclusion. At that point, it looks easy. The opening summary is, Abraham had two sons from two women. The closing summary is, we are the children of the free woman, not of the slave. Well, OK, how do you get from there to there? Well, how a conjurer does something simple, the flick of a wrist, to achieve something complex, a flock of doves, or a pink rabbit coming out of a hat? Well, Paul here does the opposite. He achieves something very simple. All he does is to add the word we to the opening statement. We are the children of the free woman, by doing something almost unbelievably complex, namely the argument of verses 23-30. But out of that complexity, the letter's real thrust emerges. Not just the warning against going back to slavery, chapter 5 verse 1, echoing 4-8-11, the don't go back to Egypt passage, but also the denunciation of those who are presently appealing to Jerusalem and reinforcing that appeal with violence. Paul accused his rivals in 4-17 of wanting to shut out the Galatian Gentiles, and here in verse 30 he says that's what the Galatians should do to them. Some disagree. Some think he's simply stressing that we are the free people, and let's leave it at that. Others resist making verse 30 the real emphasis because the other commands there are positive. Verse 27, celebrate and shout, and their plurals stand firm, 5-1, whereas this one is negative and singular. Cast them out in the singular. But I think the emphasis is clear. Paul's quote of Genesis 21-10 in verse 30, cast out the slave woman and her son. I think that's what he wants to say, and he lets Torah say it.