Only a Ghost! by Irenæus the Deacon is a humorous fictional travelogue written by Sabine Baring-Gould. The ghost of Irenæus the Deacon of the church of the 4th century Jerusalem visits London, the 'most religious city of the world' in 1870. Baring-Gould described Irenæus' astonishment on the state of hypocritical, superficial and superstitious 'Christianity', and their astonishment in return on the unwarranted thoughts of Irenæus'.