By Grace Through Faith (v. 1-10)
You used to do bad things just like everybody else, but now you walk with Christ because God loves you and showed mercy on you. You have been saved through faith, but it is not your own doing. God loved you and created you in a way that you would follow Christ and be saved, so you shouldn't boast about it.
The idea that you shouldn't boast about being among the saved seems very good, from either perspective. If you are an outsider and the Christians are constantly boasting, they will likely come off as jerks, being around a bunch of people like that can be very troublesome. From the Christian perspective, if you are boasting you might turn potential converts away which would be bad for you. So in either case, encouraging Christians to not be boastful seems like a good thing.
Another thing here, this says that God made you in such a way that you are saved because "you are his workmanship" and he loves you. But he created you in such a way that you will be saved before you existed. This seems very strange to me because there do exist people who will not be saved, so does that imply that he does not love them? Is his workmanship not as good in them? He knew all of that before he created them right? So why did he still create the "lower quality" people? Not sure if I'd exactly call this a contradiction or anything, but it is certainly something to think about.
One in Christ (v. 11-22)
We used to be divided, circumcised and uncircumcised, but now we are together in Christ. Jesus preached peace to everyone.
I guess it is a good message, we should all work together. Although this isn't so much a command as it is a declaration. It also seems quite incorrect, look at the huge number of different denominations, they are certainly divided on many issues, and we see a problem with faith based stuff, there is no real way to reconcile a disagreement. "I believe X and you believe Y, we both believe it because of faith so there is no convincing each other...uhh...kill each other?" Also, it is simply incorrect that Jesus taught peace to everyone.
For the overview post (If you think I should add or remove stuff from this list please let me know, I think it would make good conversation)
2:8-9 Don't boast about being among the saved