Knowing the congregational context, I certainly don’t think it was taken in the first way you suggest. I doubt anyone heard they were “bad americans.” I rarely use seminary examples, but as I was preaching in my home congregation who asks regularly about my seminary process, and takes an interest in what I’m learning, I think the one seminary section was actually helpful. And do note it sets up a Jesus punch line, which is the whole point. Overall, that congregation is way too educated for its own good and they value sermons with a bit more zest than might some congregations.

I sense, however, a larger distinction we may have over who is made one in Christ. Does Christ’s reconciling action only apply to those who confess certain words and ask Jesus in her heart, or does Christ’s life and death reconcile the whole world–cosmos–to himself? I’m not saying you’re suggesting a limit. Just that I, on the other hand, am eager to explore how Christ affects our relationship with every person in the world, even and especially those who do not yet know him fully.

Peace.

Too bad that’s not what St. Paul meant.
Christians are one in Christ.
The trouble is that Christians are often divided, as they focus on their own self-interests.
The good news (Gospel) is that Christ will always be the unifying force of the church. Jesus became our Savior so that we may be unified. We are baptized and called Christians because God has desired to make us one in Christ. St. Paul reminds us that we need to recognize our selfishness, our desire to do our own thing and to come together as one body in Christ.

Yes, as you mentioned, the message is as contemporary as it was in Paul’s time. We have the same tendency to separate ourselves or to be divisive; but Christ is still the remedy for this divisiveness. He forgives our sins. He is still our Savior. He is still the reason we go forth from here resolved to do what is right, to seek unity among ourselves–whether here or at home.

Praise be to God, who has made us one in Jesus’ name.

Good luck.