The article calls for critical theological examination of the politics of ethnicity in the context of mainline churches in South Africa. The category of ethnicity is largely missing in the interrogation of diversity in the delineated context. Including this category of difference in the theological and religious studies diversity discourse would, if brought to bear on praxis, facilitate the building of inclusive worship spaces. On the contrary, neglecting the politics of ethnicity in the context of churches means neglecting a dynamic that impacts negatively on the everyday life of ordinary churchgoers. The argument is based on ethnographic fieldwork conducted by the author in a Methodist church in Johannesburg primarily in 2009.