According to CIA World Factbook, the people of Republic of the Congo are largely a mix of Catholics (33.1%), Awakening Lutherans (22.3%) and other Protestants (19.9%). Followers of Islam make up 1.6%, and this is primarily due to an influx of foreign workers into the urban centers.

Answer this question, if possible (if impossible, reply "unanswerable"): What religion is notable due to an influx of foreign workers in the rural areas?
unanswerable