Historians and theatre practitioners have accepted the belief that theatre evolved from the ritual and particularly the Greek ritual. At the religious festival of Dionysus (Greek god of wine and fertility) the Dithyramb (hymn performed by a chorus) was the start of theatre in the 7th century BC. Later an actor stepped forward to perform alone. Eventually Sophocles used up to three actors performing a play as we know it today. Well known plays like Antigone and Oedipus Rex had more than three characters that were all performed by only three actors.
During the Dark Ages (around 476 - 1000 AD) the church condemned the theatre and only a few "wandering performers" continued performing. Some of them worked as Jesters in the palaces of kings or the castles of the noble landowners. No formal theatre like in the Greek and Roman times existed anymore. Actors had a very low status and were perceived as evil. For many years women in theatre were associated with prostitution and decadence.
Ironically it was the church during the Medieval Times that was responsible for the rebirth of theatre. The church and the government at this time were one and the same. Not belonging to the church made you a social outcast. People were illiterate and church services were in Latin. The visual aid of a performance helped the people of the time to better understand the sermons. Mystery plays were based on bible stories like the birth of Christ. Allegorical morality plays had story lines that were always about man and how he succumb to sin. During performances there were definite mansions (setting) for heaven and hell. The goal of morality plays were to show man what will happen if he continues to live in sin by sending him to hell or if he changed his life and repent he will go to heaven. Everyman (author unknown) is the best known and one of very few Medieval plays that survived.
Eventually theatre became more secular and moved out of the church to either a fixed stage (similar to the stages we know today) or a pageant wagon. During the Renaissance the works of Shakespeare started a new era in theatre and from there on theatre blossomed during periods of Realism, Surrealism, Existentialism to the Eclectic and very exciting styles of modern times.