Devil’s advocate

This phrase originated in Roman Catholicism. A candidate for sainthood would be represented before the papal court by two spokesmen, the advocates against canonization or beatification, and the advocaus dei, who would make as strong a case as possible in favor of canonization. Nowadays the term is widely used to describe any person who is usually found on the wrong or losing side in any controversy, especially one who takes such positions out of sheer cantankerousness.