The lawyer was trusting in his ability to perform. The problem is that he knows that he cannot fulfill this requirement if it means all it could mean. In trying to justify himself, he sought an exact meaning of “neighbor”, so as to have a formula for righteousness. He wanted to know the letter of the Law. In other words, what he was really trying to do was get a license to be able to love only those he must in order to inherit eternal life, and to necessarily exclude all others, at his personal discretion.
To the letter, this is how mischievous children try to get around the restrictions of their parents. Think about the child whose mother tells her that she cannot ride her bike to the park; she goes anyway, and when her mother scolds her, she cries, “I didn’t ride my bike, I walked”. Can you see how childish and utterly ridiculous this lawyer is being in this passage now?
Still, we see that today many have not taken this lesson from Jesus. He is interested in the spirit, not simply our actions but our attitudes, the truth in our hearts (2 Corinthians 3:3-6). Christians have been deceived into jumping through spiritual hoops, thinking that they have earned the favor of God (Luke 17:10). That is trusting in our performance, not trusting in Jesus.
By showing us the priest and the Levite specifically, Christ was definitely trying to convey something even more than the fact that being a neighbor means more than your own kind. Christ is putting his second commandment above prior duty. Be looking for God to send someone by at the “wrong time”. Your agenda is never as important as God’s. Remember, being faithful in a little thing is a big thing. Think of those that walked on by. They thought they had bigger and more important things to do, but they missed the ministry just lying there waiting to happen.