The wall-mounted safe, which contained 22 items of Communion silver including patens, covered jugs and chalices, was taken from a small room inside St Luke's Church in Linch Road.
The theft is believed to have happened some time between 11am on Sunday, August 22, and 2.30pm on Friday, August 27, when the church warden went to retrieve the silverware for the Sunday service and discovered the safe was missing.
Detective Constable Della Puttock said: "This was a large, valuable haul which was stolen from an unmanned rural church. We are appealing for any witnesses who may have seen anything suspicious, or who may have seen any of the stolen items, to contact us."
The stolen hoard amounts to a representative selection of ecclesiastical silver from the late 17th to the mid 20th centuries with the more identifiable antique items including an hexafoil salver inscribed The Gift of Mr Samuel Knight, Cutler to the Parish Church of Wellingborow, 1728 and a George I quatrefoil paten of the same period.
Anyone with information should contact Sussex Police on 0845 60 70 999 quoting the crime reference number 518/29/08/2010.