Official Bahá'í Funeral Service for Believers Only

"An official Bahá'í funeral service should only be given for a believer, but there is no objection to the reading of Bahá'í prayers, or indeed to a Bahá'í conducting the funeral service of a non-Bahá'í, if this has been requested."

(From a letter written on behalf of the Guardian to the National Spiritual Assembly of the United States, July 20, 1946)

http://bahai-library.com/hornby_lights_guidance&chapter=2#n657