For Shakespeare, all the world was a stage, and the men and women merely players. But he took that only to the level of observation. It took a Spaniard, Pedro Calderon de la Barca, to take that to the fullest possible lengths, in The Great Theatre of the World, written in 1635. It is a short, action-packed play in which entire lifespans of a society - from king to beggar, rich merchant to peasant - are explored.

God here is the omnipotent director, who appoints his stage manager, "The World", and selects his players and their roles (not individuals, but archetypes). Then, in line with the doctrine of free will, he pushes them on stage. From the cradle to the grave, they're free to chart their own choices; only then will the Supreme Being intervene again to decide their ultimate fates.

The similarities to medieval mystery plays are obvious, and played up in the production that opened last night at the Arcola Theatre in east London, in set and staging, but what does this say to a 21st-century secular Britain? The adaptor, Adrian Mitchell, says that although he's an atheist, he felt that there was a truth in the play that transcended religion, and a wit that translated to the modern age.

Of wit there's certainly plenty, particularly in such Falstaffian scenes as that in which the actor appointed to play the peasant, Kristian Dawson, tries to get out of the role with a string of excuses, including that he's "scared of cows". The verse is turned, effectively, to rhyming slapstick at such moments - to ask God "to leave me out would be thought rude,/ by a director of your magnitude".

As the beggar, played with force and passion by Aoife McMahon, trails with increasing desperation around the heedless king and court, like a Big Issue seller on a bad day, you can't but feel that Mitchell has also found something beyond entertainment. And yet "the poor have it rough" doesn't really take the audience so far. What meaning can really be drawn from this omnipient, anthropomorphic creator who treats his efforts as mere playthings - more in line it would seem with the Olympian Gods than the Christian saviour?