Special Collections and Archives is the repository for the records of a number of churches and religious bodies. These are described in:
A Guide to Original and Copied Records of Religious Organizations, Largely New Jersey Churches, in the Special Collections and University Archives of Rutgers University. Donald A. Sinclair. New Brunswick, N.J. : Genealogical Society of New Jersey, 1999. Available?
The Jewish Historical Society houses the records of a number of synagogues in the MetroWest area (Essex, Morris, Sussex, and portions of northern Union counties). Click on "Archives" and then "Finding Aids" to see lists of available collections.