What are the similarities among an oratorio, a mass, and an opera?

The musical
forms of oratorio, mass, and opera generally share many similarities. One of the most obvious is
orchestration. All three are most often associated with large forces of instruments accompanying
voices. The voices usually include both soloists and a full SATB (soprano, alto, tenor, bass) .
All three are also creations of European culture from roughly the same time period (all three
had achieved full fruition by the late Baroque). Not only were they creations of European
culture, but they also were also funded by the Church, as were most of the arts, until the early
nineteenth century. The mass is the most obviously religious of the three forms. It usually
follows the setting of an ordinary mass: Kyrie, Gloria, Credo, Sanctus, and Agnus Dei. The
oratorio is also most often religious in nature, with the most famous being The
Messiah . The mass and the oratorio are also similar in that they are not dramatic
forms of music. That is not to say that they lack emotional power....