This study examined the challenges of Sudan Interior Mission (SIM) pioneer missionaries in Nigeria. The main objectives of this research were to investigate the missionaries’ challenges and know how they were able to overcome those challenges in the Sudan. The methodology was a historical research method, using historical records and documents. The findings revealed that discouragement from the missionary colleague based in Lagos was the first challenge encountered by the pioneer missionaries. Followed by a communication barrier. At first, they were using an interpreter to preach, but later committed themselves to learning native languages to break the language barrier. The study also showed that the challenge that missionaries faced in Nigeria was the hot weather conditions and unconducive climate; they were not used to hot weather, and they found it difficult to acclimatise to the weather, and as a result, some returned home. The study concludes that the controversial area was disagreement between European missionaries and Africans people. They saw Africans as people without culture and wanted to impose their culture on them, which resulted in the founding of African indigenous churches. The study recommends that Culture is the way of life, and Africans' way of life is different from the West, so Europeans should not look down on the African way of life, because names such as paganism, primitive, uncivilised, and barbaric are misrepresentations of African culture.
Keywords: Missionaries, culture, Languages, challenges, and Mission