Jesus taught us that we should “love the Lord thy God with all thy heart, and with all thy soul, and with all thy strength, and with all thy mind; and thy neighbour as thyself” (Luke 10:27). This principle is not new. Neither is the concept of who our neighbour is. After all, when asked to clarify who constitutes our neighbour, Jesus went on the give the parable of the Good Samaritan.
Following the parable, Jesus asked, “Which now of these three, thinkest thou, was neighbour unto him that fell among the thieves?” They responded that the one who showed mercy was the neighbour. Given that the Samaritan was the neighbour because he showed mercy, it would seem on first reading that Jesus is telling us we should love those who show mercy to us.
Not so fast though. If Joe Brown lives next door to me, most consider him to be my literal neighbour. At the same time, most would consider me to be his neighbour. In the same vein, not only was the Samaritan the beaten man’s neighbour, but conversely, the beaten man was the Samaritan’s neighbour.
I think it behooves each of to love not only those who show us mercy, but to be the ones showing the mercy.
or in other words practice what you preach
I don’t quite accept that the “first reading” you gave is the obvious one. Neighborship is such a completely reciprocal relationship that you can’t say A is B’s neighbor without simultaneously saying that B is A’s neighbor. I think that understanding is built into the parable, and I think the parable is directed at those who have the opportunity to show mercy, not at those who have the opportunity to be grateful for mercy.