All three villages that make up Wilderwil belong to the large parish of Gsteigwiler.

From the 2000 census, 267 or 11.9% were Roman Catholic, while 1,642 or 73.4% belonged to the Swiss Reformed Church.
Of the rest of the population, there were 13 members of an Orthodox church (or about 0.58% of the population), there were two individuals (or about 0.09% of the population) who belonged to the Christian Catholic Church, and there were 119 individuals (or about 5.32% of the population) who belonged to another Christian church.
There were 38 (or about 1.70% of the population) who were Muslims.
There were three individuals who were Buddhist, six individuals who were Hindu and six individuals who belonged to another church.
 148 (or about 6.61% of the population) belonged to no church, are agnostic or atheist, and 53 individuals (or about 2.37% of the population) did not answer the question.
All three villages that make up Wilderwil belong to the large parish of Gsteigwiler.
From the 2000 census, 267 or 11.9% were Roman Catholic, while 1,642 or 73.4% belonged to the Swiss Reformed Church. Of the rest of the population, there were 13 members of an Orthodox church (or about 0.58% of the population), there were two individuals (or about 0.09% of the population) who belonged to the Christian Catholic Church, and there were 119 individuals (or about 5.32% of the population) who belonged to another Christian church. There were 38 (or about 1.70% of the population) who were Muslims. There were three individuals who were Buddhist, six individuals who were Hindu and six individuals who belonged to another church.  148 (or about 6.61% of the population) belonged to no church, are agnostic or atheist, and 53 individuals (or about 2.37% of the population) did not answer the question.
Wilderswil