April 22

…although the Book of Revelation has not been interpreted in the teachings from beginning to end there are many passages of it which have been interpreted. It is a very important book and very important in teaching the Bahá'í interpretation of certain Biblical passages to devout Christians. 
(From a letter date 13 August 1944 written on behalf of Shoghi Effendi to an individual believer; Memorandum from the Research Department of the Universal House of Justice dated 7 January 1986)