On 7 September 1939, in a declaration and written statement submitted to the local Belgian colonial administrator at Madimba (~ 90 km from the Belgian Congo capital Leopoldville), he and several hundred followers sent a message to the colonial masters that their days in the territory they occupied were numbered, and that the time had come for liberation and for natives to look after themselves.
and some were conscripted to fight in World War II alongside Belgian troops, Mpadi was sent to serve his sentence at the Central Prison of the then Elizabethville (now Lubumbashi, Katanga province).
The movement later came to be known as the "Eglise des Noirs Afrique" (Church of Black people in Africa), with its headquarters at Ntendesi, later Songa-Ntela near Kasangulu, DRC.
Mpadi's sermons and religious message emphasized the messianic and prophetic leadership of Simon Kimbangu as the liberator of all Black people in the world.
From the mid-70s, though still monotheist he oriented his movement towards more traditional beliefs and history of past African prophets and warriors, no longer referring to Christianity or the Bible.