Jeremiah Allen is a character in DEXTER. He is a reverend, and one of the religious "nut jobs" who Joey Quinn and Angel Batista were sent to interview during the course of the Doomsday Killer Investigation. During their first attempt to contact Allen, Quinn and Batista were given a false address and end up waiting in the car, discovering that Angel's going through a mid life crisis and in addition the two men spot a blunt hidden in the new car he's picked up. The two decide to get high and have a comical moment when they finally receive the call to locate Jeremiah Allen.
When thet finally do manage to contact Allen, Miami Metro Homicide gets a new lead in the DDK case in the form of a possible suspect, Professor James Gellar, a professor from the University of Tallahassee and a revelations expert who Allen is obsessed with. Gellar went "underground", three years ago he was accused of stealing an Ancient Sword that originally belonged to John the Revelator, the man responsible for writing Revelations. Debra Morgan deduces that this may have been the sword used in the DDK murders of Omar Rivera and Nathan Roberts.