It was, and many miss the point of the story. The Samaritan was not a Jew. Indeed, Samaritans were badly treated by many Jews in that time. Yet...while other Jews passed by the man who had stumbled...it was a Samaritan, an outsider, who stopped to help.
I've seen a lot of people who don't understand the reason for Jesus to tell that parable. Once you know the truth, however, it becomes clear. The Samaritan, an unbeliever, was the one who helped the man, while some of his own passed him by.
A guy just doesn't know who's going to render aid, I guess.
The Samaritans were Jews, but their blood and beleifs had mingled with the surrounding pagans, and so they were despised by the "true" Jews.