West Sussex on Wikipedia.

Aldingbourne, St. Mary the Virgin. © David and Pat Halliday.
Angmering, St. Margaret. TQ 067 043. From a postcard in the Kevin Gordon Collection. Link.
Ardingly, St. Peter. TQ 339 298. © Kevin Gordon. Link.
Arundel.

Balcombe, St. Mary. TQ 307 309. © Kevin Gordon. Link.
Barnham, St. Mary the Virgin. A close-up of the church. From an old postcard, Bulman Collection. Previously in the Unknown section, thanks to Noel Walley for identifying this church. Link.
Billinghurst, St. Mary. From an old postcard (franked 1913), Bulman Collection. Link.
Bolney, St. Mary Magdalene. TQ 261 226. From an old postcard, Bulman Collection. A modern view. © Kevin Gordon. Link. Village Chapel (CoE). TQ 263 235. © Kevin Gordon. Link.
Bosham, Holy Trinity. © Phil Jobson. Link.
Boxgrove, St. Mary & St. Blaise. The church now serving as the parish church was originally only a part of the much larger Priory, the ruins of which are also visible in this old postcard from Steve Bulman's Collection. A modern view. SU 908 075. © Kevin Gordon. Link1. Link2.
Bramber, St. Nicholas. An inside view. Both from old postcards, Brett Jeffery's Collection. Link.
Broadwater, St. Mary. From an old postcard in Steve Bulman's Collection. A modern view. © Graeme Harvey. Link.
Buncton, St. Michael. According to the Wikipedia entry, a sheela-na-gig carving here was destroyed by vandals in 2004. From an old postcard in Steve Bulman's Collection.
Bury, St. John the Evangelist. From an old postcard in Geoff Watts Collection. Link.

Chichester, the cathedral, dedicated to the Holy Trinity. From an old postcard, Bulman Collection. Another old postcard, this one from Reg Dosell's Collection. Link.
Church Norton, St. Wilfrid. SZ 872 958. From an old postcard, Kevin Gordon's Collection. A modern view. © Kit Heald. Link.
Clayton, St. John the Baptist. TQ 299 140. © Tony Preston. Link.
Climping, St. Mary. TQ 003 026. From the postcard collection of Kevin Gordon. Link.
Compton, St. Mary. © Juile Brutnell.
Crawley, St. Michael & All Angels (currently closed). © Peter Morgan. St. John the Baptist. From an old postcard (franked 1904) in Steve Bulman's Collection. Link. Islamic Centre and Mosque on London Road, Langley Green. TQ 270 385. © Mehmood Naqshbandi, and reproduced from his website Muslims in Britain.
Cuckfield, Holy Trinity. TQ 303 244. © Kevin Gordon. Link.

Eartham, St. Margaret. SU 938 093. © Kevin Gordon. Link.
East Grinstead, St. Swithun. From an old postcard (where it's spelled Swithin), franked in 1919, Bulman Collection. Link.

Ferring, St. Andrew. TQ 094 026. From a postcard in the Kevin Gordon Collection. Link.
Findon, St. John the Baptist. From an old postcard in Reg Dosell's Collection. Link.
Fittleworth, St. Mary. From an old postcard in Geoff Watt's Collection.
Forestside, Christ Church. © Julie Brutnell. Link.

Goring-by-Sea, St. Mary. TQ 111 026. From a postcard in the Kevin Gordon Collection. Link.

Hardham, St. Botulph, which Kevin says has exceptional wall paintings. TQ 039 176. © Kevin Gordon. Link.
Haywards Heath, St. Wilfred. From an old postcard, Bulman Collection. Methodist Church. 198 TQ 331 244. © Dave Westrap. Link.
Heyshott, St. James. Another view. Both from old postcards in Reg Dosell's Collection. Link.
Highbrook, All Saints. From an old postcard in Steve Bulman's Collection. Link.
Horsham.
Horsted Keynes, St. Giles. From a 19th century engraving, courtesy of the Colin Waters Collection. An old postcard view, from Reg Dosell's Collection. Link.
Hurstierpoint.

Ifield, St. Margaret. TQ 247 376. From an old postcard, Bulman Collection.
Itchingfield, St. Nicholas. From an old postcard in Reg Dossell's Collection. Link.

Lindfield, All Saints. From an old postcard, Bulman Collection.
Littlehampton, St. Mary. From an old postcard, Bulman Collection.
Lyminster, St. Mary Magdalene. TQ 023 048. From the postcard collection of Kevin Gordon. Link.

Midhurst, St. Mary Magdalen and St. Denys. SU 887 215. From the postcard collection of Kevin Gordon. An old postcard view, from Reg Dosell's Collection. Link.
Milland, St. Luke. From an old postcard, Bulman Collection. Link.

Parham, St. Peter. From an old postcard (franked 1905), Bulman Collection. Link.
Petworth, St. Mary the Virgin. From an old postcard (franked 1908), Steve Bulman's Collection. The spire shown here no longer exists - see the photo on the link site. Link. At Petworth House a once separate chapel was built into the fabric of the house. Three interior views - 1, 2, 3, all © Steve Taylor. SU 976 218. Link.
Pulborough, St. Mary. Another view. TQ 047 187. Both © Steve Taylor. Link. St. Crispin & St. Crispinian (R.C.). Another view. TQ 046 188. Both © Steve Taylor. Link (very slow when I tested).

Rogate, St. Bartholomew. From an old postcard, Bulman Collection.

Selham, St. James. SU 933 207. From the postcard collection of Kevin Gordon. Link.
Selsey, the Chapel of St. Wilfrid at Church Norton. SZ 872 957. From a postcard in the Kevin Gordon Collection. Link. St. Peter. From an old postcard in Reg Dosell's Collection. Link.
Shoreham-by-Sea, St. Mary. From an old postcard, Bulman Collection. Another old postcard view, this one from Reg Dossell's Collection. Link.
Slaugham, St. Mary. From an old postcard (where the text says Slaughan), Bulman Collection. The scanned image had to be heavily processed to get even this poor quality image. Link.
Slindon, St. Mary. SU 961 083. © Kevin Gordon. Link.
Sompting, St. Mary. Simon describes the spire as "Rhenish helm", which is confirmed in Betjeman, who adds that it is unique in England. © Simon Kidner. A view from the 1930's. Illustration from the Colin Waters Collection.
Steyning, St. Andrew. TQ 179 114. From the postcard collection of Kevin Gordon. Link.
Storrington, St. Mary. From an old postcard (franked 1905), Bulman Collection.
Sullington, St. Mary. From an old postcard, Bulman Collection. Link1. Link2.

Tangmere, St. Andrew. From an old postcard, Bulman Collection. Link.
Terwick, St. Peter. From an old postcard, Bulman Collection. Link.
Trotton, St. George. From an old postcard, Bulman Collection. Link.

Up Marden, St. Michael & All Angels. SU 795 142. © Kevin Gordon. Link.

West Dean, St. Andrew. From an old postcard in Reg Dosell's Collection.
West Grinstead, St. George. From an old postcard in Reg Dosell's Collection. Link.
West Itchenor, St. Nicholas. © Juile Brutnell.
West Thorney, St. Nicholas. From an old postcard, Geoff Watt's Collection. Link1. Link2.
Wisborough Green, St. Peter ad Vincula. TQ 052 259. From a postcard in the Kevin Gordon Collection. Link.
Worth, St. Nicholas. TQ 302 362. © Rick Williams. Link.