This is apparently a true story, recounted to my Zen teacher by the missionary to whom it happened.
A Christian missionary came to an aborigine tribe whose members have never heard of Christianity before. Having seen them practice many things that were a no-no to any good Christian, he started teaching them about Christianity. He also told them they had to change much of their behavior, otherwise they would end up in eternal damnation.
One day, the chieftain called the missionary and asked him if God was going to condemn people who were not following his teachings, providing these people had never heard of Christian teachings.
The missionary explained that God was merciful and would never condemn a person acting out of ignorance. As long as that person had never heard the Word of God, God would forgive him his sins.
The chieftain looked the missionary straight in the eyes, and said: "Then why did you come?"