He was possibly the first convert to Christ in the Congo. Mantantu Dundulu was a young man protecting his three sisters who began to assist a Baptist missionary named William Bentley. It was on April 30, 1882, that Mantantu became a Christian and this action cut him off from his tribe as they still practiced demonic rituals. His birth name meant “sorrow” and “stupid” so Bentley started calling him Nlemvo (meaning “obedient”). Bentley taught him to read English and Nlemvo, in turn, assisted greatly in helping Bentley create a dictionary and translate the New Testament (and portions of the Old) into the Kikongo language. Although he never was fully accepted back into his tribe, he did marry and then he continued exploring the Congo with Bentley and other missionaries to preach the gospel.
As he got older, Nlemvo went blind but then learned braille. Even suffering blindness, he continued to aid in translation work. As he got older he was viewed more and more as a statesman and was sought out to resolve disputes. It is estimated that, by his death in 1938, 200,000 Congolese had accepted Christ.