This is a simple and beautiful church chorus (a simple call-and-response church hymn sung in an Africanized folk style) with lyrics taken from a longer hymn text.
Like other songs of the genre, it is performed not just in church but at concerts, parties and in all kinds of social settings. One of our favorite renditions of Modimo rea go boka occurred during a stay in a game preserve near South Africa's border with Zimbabwe, when we were led by a group of local teenagers in a spirited version of the hymn while dancing in a line around the barbeque [braai] pit.