It seems by the way Jesus told the story, that one need not be a christian to inherit eternal life. Jesus was asked this question and after the parable answered " Go and do likewise". Now the good samaritan was not a christian, but a product of mixed interbreeding between jews from the Northern Kingdom and other people after Israel's exile. They were considered heretics. Yet, it was what was in the samaritans heart that was the focal point of the parable. To say that only christians ( only people who accept Jesus as their Lord and savior and accept that he died on the cross for their sins) are going to be saved, is in a way like, judging other people. And as you well know, Jesus clearly states "judge not, least you yourself be judged.
Amen and God bless everyone.