Nzambi a Mpungu
Nzambi a Mpungu is the Kikongo language name for a high creator god. He is mentioned as the name for God as early as the early sixteenth century by Portuguese visitors to the Kingdom of Kongo. This deity has been known as the high and creator god from before this time until today.
European missionaries along with Kongo intellectuals (including King Afonso I of Kongo) set out to render European Christian religious concepts into Kikongo and they chose this name to represent God. Jesuit missionaries in the 1540s noted the acceptance of this relationship as well, and it was probably included in the now lost catechism produced by Carmelites in Kikongo in 1557. Certainly it was used for God in the catechism of 1624, a translation by the "best masters of the church" in Kongo under the supervision of the Jesuit priest Mateus Cardoso.
It is not clear if the elevation of Nzambi a Mpungu to the status of creator god and equivalent to the Christian God by priests and missionaries was the reason that he is regarded as such by modern Kongo cosmology, or whether he was always considered the creator. However, in the Kingdom of Loango, a Kikongo-speaking area that never accepted Christianity as its national religion, reports by Dutch visitors also gave this as the name for God.
Thornton, John K. "The Development of an African Catholic Church in the Kingdom of Kongo, 1491-1750," Journal of African History 25 (1984)