What is the origin of the idiom "moment of truth" and when to use it?

The origin of the idiom "moment of truth" can be traced back to Spain's bullfighting tradition. In bullfighting, the "moment of truth" or "el momento de la verdad" refers to the climax of the fight when the matador faces the charging bull. It is the crucial moment that determines the matador's skill, courage, and ability to execute the final decisive moves. It is commonly used in personal, professional, and societal contexts to describe significant events that expose the truth or reality of a situation, such as a key moment in a trial or a critical point in a social movement.