What is the origin of the idiom "devil's advocate" and when to use it?

The idiom "devil's advocate" is believed to have originated in the 16th century. It is thought to have come from the Catholic Church's canonization process, in which a church official known as the "promotor fidei" (promoter of the faith) was tasked with arguing against the canonization of a candidate. The promotor fidei's job was to play the devil's advocate, presenting all the negative evidence against the candidate in order to ensure that the decision to canonize them was made carefully and objectively. This expression is used to describe someone who intentionally takes a position that is opposed to the majority opinion in order to stimulate debate or discussion.