What defines an oratorio?

An oratorio is defined as a large musical composition that typically focuses on a religious theme. This genre originated in the early Baroque period and combines vocal and instrumental music, including soloists, choruses, and orchestras. The subject matter of oratorios often draws from biblical stories or significant religious events, with the music designed to express the emotions and spiritual dimensions of these narratives vividly.

It is notable that an oratorio is not staged like an opera, meaning it is usually performed in a concert setting without costumes or elaborate staging. This distinguishes it from works that are purely theatrical or drama-based, such as what would typically be associated with operas or musical dramas. Therefore, the focus on a religious theme with a large-scale composition framework directly aligns with the defining characteristics of an oratorio.