Wagner attended a performance of Messiah at Exeter Hall in London with a chorus of 700 voices. He recorded in his autobiography:
It is here that I came to understand the true spirit of English Protestantism. This accounts for the fact that an oratorio attracts the public far more than an opera. A further advantage is secured by the feeling among the audience that an evening spent in listening to an oratorio may be regarded as a sort of service, and is almost as good as going to church. Every one in the audience holds a Handel piano score in the same way as one holds a prayer-book in church. These scores are sold at the box-office in shilling editions, and are followed most diligently–out of anxiety, it seemed to me, not to miss certain points solemnly enjoyed by the whole audience. For instance, at the beginning of the “Hallelujah” Chorus it is considered proper for everyone to rise from his seat. This movement, which probably originated in an expression of enthusiasm, is now carried out at each performance of the Messiah with painful precision. (1)
Source: Holmes, John (1990) Composers on Composers. New York: Greenwood Press, p. 73-74.