Alsunga is the center of the Suiti, a small Catholic community in the Lutheran western part of Latvia.

In 1561 Alsunga became the part of the predominantly Lutheran Duchy of Courland and Semigallia.

In 1623, the local landowner, Johan Ulrich von Schwerin, in order to marry a Catholic court lady Barbara Konarska from Vilnius, agreed to himself become Catholic.

After the marriage he lived in Lithuania and Poland until 1632, when he returned to Alsunga after his father's death.

In 1634, Johan Ulrich invited Jesuits to establish a mission in Alsunga to help him transfer all his peasants to Catholic faith.