“Only God knows how many Catholics there are in Mauritania”, says Bishop Martin Happe, from the capital Nouakchott, with a smile. Born in Germany, he belongs to the Missionaries of Africa (White Fathers). In a conversation with the international pontifical foundation Aid to the Church in Need (ACN), he looks back over 50 years of involvement with Africa – first in Mali and then, for the last 28 years, as the only bishop in the west African state of Mauritania, whose 4.5 million inhabitants are almost 100% Muslim: “They are automatically Muslim, just like in my childhood you were automatically Christian in my home country.”