Update: The Malta Independent reports the passenger was a Caribbean Christian. (h/t eats shoots 'n leaves)
Via Times of Malta:
An Air Malta flight from London Heathrow had to return to the terminal this afternoon following a disturbance by a passenger.
The man got to his knees and started chanting, apparently in Arabic, and ignored instructions by the purser to return to his seat.
According to reports there was a 'panic' among some passengers. The aircraft returned to its terminal slot.