I have recently come to suspect that this parable is somewhat poorly stated.
Traditionally, the interpretation of this parable is that everybody in the world is your neighbour, even your worst enemy (such as a Samaritan might be a Pharisee's worst enemy), so you have to love everybody in the world as you love yourself in order to get into heaven. Something I am bang alongside, regardless of my personal beliefs about heaven.
But that's not what the passage says. In the story, this guy gets mugged, and gets ignored by a priest and a Levite, but the Samaritan helps him. And it's made clear from the quick follow-up Q&A that Jesus has with the Pharisee that it was the Samaritan who was the muggee's neighbour; NOT the other two guys who ignored him.
Which implies that your "neighbours" are in fact only those who act neighbourly towards you. A different lesson entirely.
What conclusions can we draw from this? Either 1) the story was told wrongly, 2) the story was written down wrongly, or 3) the story is consistently being interpreted wrongly. But certainly also 4) when studying religion, keep your brain turned on.