Through the seven centuries (950 to 1570 A.D.) when the Mystery Plays flourished, all initiatives were faith-based, whether they emanated from church or state. In a rigidly unified and stratified society, most Europeans believed Christian dogma, and heaven and hell were powerful realities. The first plays were created and acted by the clergy, based on biblical narratives, to edify largely illiterate congregations, but when their production was taken over by the trade guilds, secular values crept in, including lavish spectacle, comic horseplay, satire and parody. Nevertheless, the plays seem to belong to a world radically different from our own, as surprising in their sophistication as in their naiveté. Kemp’s adaptation hews to the original material wherever possible, with the Middle English occasionally translated for clarity. Director Michael Nehring steers a tricky course among the varied materials, and he’s well-served by a passionately dedicated cast of 12. Paul R. DeDoes’ set is a sort of jungle-gym for actors, making for an athletic performance, but providing poor sightlines.