a Samaritan (v.33)--While priests and Levites had distinguished places in Jewish society, Samaritans were despised as half-breeds who had blended the worship of God with pagan practices. This term was used as an insult to describe a Jew who did not pay strict enough attention to religious tradition (Jn 8:48). While the roots of this prejudice reached back to the conquest of the northern kingdom of Israel by the Assyrians in 722 BC, this ancient animosity was fresh in Jesus’ day because some Samaritans had recently defiled the temple in Jerusalem by scattering bones in it. Prayers were offered daily that Samaritans might not be given eternal life.
So what I am saying is, from this parable Jesus does not despise the good works of non-believers or those who don't believe in the just the correct way. He even held one up as an example of charity. Think about it.
Charity yes, Salvation no. The context of this parable is teaching the Jews that their neighbor could be anyone, not just those who share the same belief system, or racial background. The parable was in answer to the question "...who is my neighbor?" (Luke 10:v29), and brings the questioner to come to the conclusion that Jesus wanted them to come to "Which ... was neighbour unto him that fell among the thieves?"(v36). And he said, "He that shewed mercy on him."
If this was a prerequisite for Salvation, then why does Jesus say in John 14:6 that "... no man cometh unto the Father, but by me."?
Don't confuse charity with Salvation. There are a lot of people who are very charitable, who could care less about Christ. For example there are a lot of practicing Jews who are very charitable, but they flatly deny Christ. In the Christian life charity (love) is one of the outward manifestations of the Holy Spirit's work in our lives (see Galatians 5:22).