If the someone in your church has this as his or her official name, then it IS a real name because it is the legal designation of a real person, no matter what its origin.
Deverin is a surname in use in both the United States and
France. I have not been able to find its etymological origin, but here are some references to individuals with the surname Deverin:
Sean P. Deverin, biologist
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1302267
Jean Deverin, Scrabble tournament player
http://www.cross-tables.com/results.php?p=11707
Yveline Dévérin Lecturer in Geography, University of Toulouse-le-Mirail,
Francehttp://www.worldhunger.org/articles/06/africa/deverin.htm
And for a use of Deverin as a first name, there is Deverin
Karol, who has worked in casting on Hollywood films and was also the screenwriter of the film
Momentum:
http://www.imdb.com/name/nm0007172/