I have collected a little information about Lewes. These links should allow you to form your own conclusions about it. My own impression is of a night carnival, masses of firecrackers, five brilliant displays, destruction of tableaux of irritating personalities (Pokemon?!), and an element of anti-papistry. (I deliberately choose an archaic expression).This site has links to various sites with background to the bonfire societies in and around Lewes. Some of them are hosted by a familiar name, which I had no reason to recognise when I first bookmarked it. But they include material from the societies, with their own views of themselves.
I don't know about local church involvement - I'm of local extraction, but never resident there.
This page includes a background to the history, but also a feedback page, which includes a posting from a society member.
This book is written by a local, and a Catholic who has a better understanding than I.
Streets of Fire: a Hymn to Lewes and the Bonfire Celebrations, Andy Thomas. Paperback (20 October, 1999) SB Publications; ISBN: 1857701933
Most of what happens has very little religious element, and some of what there is is anti-clerical rather than anti-catholic.
The Guardian www.newsunlimited site for last Wednesday, in the Society section, has an article covering the issue.
The tar barrels, by the way, are mostly oil-drums, halved along the long axis. I believe that once upon a time, barrels were rolled down the steep hill into the river.
Penny