John Allen Chau, the 26-year-old American missionary who was killed by indigenous people this month after sneaking onto North Sentinel Island in the Bay of Bengal.
The island is inhabited by a few hundred people whose ancestors are believed to have migrated to the Andaman archipelago from Africa 50,000 years ago. The Sentinelese have resisted all contact with the outside world.
"My name is John!" he shouted. "I love you, and Jesus loves you. Jesus Christ gave me authority to come to you."
"You guys might think I'm crazy in all this but I think it's worth it to declare Jesus to these people. Please do not be angry at them or at God if I get killed." The missionaries willing to do these things have enough passion for Christ that they see spreading Christianity as more important than preserving an unchanged culture.