Christianity in the Congo is older than the colonial period by four centuries. The Kingdom of Kongo received Portuguese missionaries in the 1480s and its ruler Nzinga a Nkuwu was baptised in 1491; his son Afonso I made Catholicism the religion of the court, corresponded with Lisbon and Rome, and had a Kongolese son consecrated as a bishop. That church was Kongolese rather than European in its texture, and it produced its own prophetic movements, of which the best documented is that of Kimpa Vita, or Dona Beatriz, who in the early eighteenth century claimed possession by Saint Anthony, preached the restoration of the kingdom and was burned in 1706.
The colonial church that followed under Leopold and then Belgium was a different institution, tied to the state through the mission schools, and the Catholic Church still runs a large share of the country's schools and health facilities. That infrastructure is why it functions as a political actor of last resort: it mediated the 2016 accord that averted a constitutional crisis, and it deployed tens of thousands of trained observers to the 2018 election and published its own count.
Beneath all of it lies the Kongo religious inheritance, which is not folklore but a working system: the minkisi, objects charged with power for specific purposes; the nganga who consecrate and operate them; and the cosmogram dividing the world of the living from the world of the dead across a water boundary. That framework travelled to the Americas with the slave trade and is visible in Cuban Palo, in Haitian practice and in the American South.