This Sunday, God-willing, I'll be preaching on the Good Samaritan (Luke 10:25-37).
The structure of the story is interesting and puzzling. I've learnt that one basic matter in Bible interpretation is that when you see a puzzle, you're getting closer to the answer. Puzzles are not to be defined away; they are to challenge our approach. The problem is not in the puzzle's existence so that the solution is to get rid of it - the problem is in the way we approach the issue - the puzzle is placed there as a bump for us to stop, consider our direction and then climb higher upon.
The question from the self-righteous lawyer was: who is my neighbour? Jesus' answer is in terms of "who was a neighbour in the story which I told?" That actually reverses the issue. It's not "who is my neighbour, so I know who to serve?", as the lawyer wanted - it's "who can become your neighbour, when you go and serve him?"
Some traditional expositions - I just read Calvin's - do appear to quickly move past the puzzle. Calvin answers "my neighbour is every human being". True enough - but is that actually what the story says? It certainly implies that every human being can be my neighbour; but it does not straightforwardly say he is - it says something more complex. It shows us someone treating his fellow man as a neighbour - and that came first. Is that reversal of the question actually the question's answer? Calvin does not consider that possibility. It puzzled me and I was looking for answers - and a quick note in the .Net Bible was where I first saw the suggestion that this anomaly is in fact actually the key.
The priest and the Levite looked at the injured man, and defined him to be outside of the category of "neighbour". So with their consciences intact, they walked by without concern of having broken God's law.
The Samaritan took a different approach. He saw the man and served him. Thus he became his neighbour.
And that's what the kingdom is like. (The lawyer's question "what must I do to inherit eternal life?" is essentially asking that question - what does the life in the Messiah's kingdom look like, and how can I obtain it?). In the Pharasaical approach, the "holy huddle" defined others to be outsiders, and then felt content to ignore their needs. In the approach of Jesus, the outsiders were embraced in love, whoever they were - and welcomed to then become insiders. The parable is not a moralistic answer to the question "please accurately define my neighbour for me?" (though that's what the questionner wanted), but an invitation to love first and ask questions later - when the love will have actually changed the situation.
That's what Jesus did for us. He didn't say "these aren't my neighbours - they're hell-deserving sinners", and then pass by, safe in the knowledge that he could do that and not be accused of any omission. He said "I'm going to make them my neighbours, however much it costs me". He came and died to welcome us in. And we should go and do likewise.