This is an interesting question. It has become accepted that a capital “D” refers to Deaf people as a culture. Lower case “d” deaf refers to deafness or hearing loss. Capital “D” Deaf people identify themselves as culturally Deaf. Lower case “d” deaf people generally do not associate with culturally Deaf people. Writing about a deaf ministry with a lower case “d” means the ministry may also include the hard-of-hearing or oral deaf people. This is fairly recent terminology and many are still unfamiliar with its use. See the following articles for more information: Terminology Describing Deaf Individuals and Deaf Culture: Big D Small d.