God's Sovereign Choice
Paul wishes he could sacrifice his place in heaven so that his brethren would make it there in his place.
A very noble desire. If everyone cared about others to the point they are willing to make sacrifices of themselves for the benefit of their neighbors the world would be a much better place. This is good stuff.
This is obviously not the way it works however. We cannot give up our spot for others, and more to the point, there are many people who do not make it to heaven. So Paul asks whether there is therefore injustice, to which he responds that there is not. God can have mercy or compassion on whomever he pleases, and he will also harden whomever he pleases. Paul then posits that someone might ask if this is unfair because no one can withstand God's will, to which Paul responds that it is up to do with us as he pleases in the same way as it is up to a potter to make one vessel for a righteous use and another for a dishonorable use.
In my opinion, Paul points out a very good question here and then doesn't really have a good answer for it. Are things fair and just? It doesn't appear so because some people receive mercy while others have their hearts hardened and are thrown into hell. Paul's response is that God created us and therefore he can do whatever he wants with us. I find this answer unsatisfying to say the least.
If I put on my Christian hat and try to defend this idea, I suppose I would say that the world is complicated and we can't know all of the details. Perhaps it is impossible to set things up in such a way as everyone goes to heaven. Furthermore, it is possible that by hardening one person's heart and dooming him to hell, many others are saved. God is looking at things on a different level than us so we can't say he is doing a poor job.
I don't think these answers are very good, but it is all I can really think of. They are in fact, some of the earliest ideas that I questioned as a child and I was never satisfied with the "God made us so he can do with us as he pleases" answer.
Paul points out that Israel tries to achieve righteousness through works (the law) and the gentiles try to receive righteousness through faith (Christ). He says that Christ is the end of the law and that righteousness is there for anyone who believes.
He basically seems to be saying that it is unfair for Israel to have to do works to be saved when gentiles don't, therefore everyone can be saved with mere belief. He also is again saying that we can get rid of the law, but that goes against what Jesus said. At least I think it does, I still don't really understand what it means for Christ to have "fulfilled the law".
If I put on my Christian hat again, I guess I would have read this passage as a really good thing because at the time I believed, and it is saying that I don't need to worry about anything, I have gotten into heaven no matter what I do from here. Looking back on that thought from my current perspective, I view this as a negative.
**disclaimer: When I put on my Christian hat, I am trying to view the passage as I think I would have when I was a Christian. I am certainly not saying this is how all Christians view it. If you have a different take on the Christian view please feel free to share.**