From SeaCoastOnline:

Don’t Sleep, There Are Snakes: Life and Language in the Amazonian Jungle
Daniel L. Everett
PantheonThe Pirahã are the “Show me!” tribe of the Brazilian Amazon. They don’t bother with fiction or tall tales or even oral history. They have little art. They don’t have a creation myth and don’t want one. If they can’t see it, hear it, touch it or taste it, they don’t believe in it.

Missionaries have been preaching to the Pirahãs for 200 years and have converted not one. Everett did not know this when he first visited them in 1977 at age 26. A missionary and a linguist, he was sent to learn their language, translate the Bible for them, and ultimately bring them to Christ.

Instead, they brought him to atheism. “The Pirahãs have shown me that there is dignity and deep satisfaction in facing life and death without the comfort of heaven or the fear of hell and in sailing toward the great abyss with a smile.”