The complicating factor the main entry raises briefly, that Christianity arrived in the Kongo kingdom in the late fifteenth century, deserves fuller treatment, since the Kongo case is one of the earliest instances of an African kingdom adopting Christianity on its own terms rather than through colonial imposition.
King Nzinga a Nkuwu of Kongo converted to Catholicism in 1491 following contact with Portuguese traders, taking the name Joao I, and his successor, Afonso I, who reigned from 1509 to 1543, became a genuinely committed Christian ruler, corresponding with the Portuguese crown and papacy, sending Kongolese students to study in Portugal and Rome, one of whom became a Catholic bishop, and working to establish Christianity as the kingdom's official religion while protesting the escalating Portuguese slave trade his kingdom was becoming entangled in. Kongo Christianity developed its own character over the following two centuries, incorporating indigenous concepts, ancestor veneration among them, into Catholic practice, and producing, in the early eighteenth century, an independent prophetic movement led by Kimpa Vita, known as Dona Beatriz, who taught that Jesus, Mary and the saints had been Kongolese before being burned at the stake as a heretic in 1706.
This two-century history, predating by centuries the colonial-era missionary Christianity more commonly associated with African conversion, is the direct context the main entry gestures toward in noting that crosses in Kongo-descended American communities may reflect Christian rather than, or in addition to, cosmogram symbolism, since the cross had already been a live, locally adapted symbol in Kongo society for two hundred years before the slave trade carried Kongo religious material to the Americas.