Between 1950 and 1970, urban development was viewed (particularly in F
rance and Belgium) very differently by urban planners and by religious
institutions, especially in the Catholic world. Urban planners saw an
opportunity to build a new environment for the self-fulfilment of mod
ern humankind. The religious institutions saw urban development as a p
rocess of de-Christianization. This difference was due not only to pra
ctical and opportunist outlooks, but was grounded in different ways of
approaching the ambiguity of the city: civilizing or destructive? Wha
t is the place of the ideal city (the ''new Jerusalem'') in Christian
thought? What is its place in modern thought? Over the uncertainties o
f the last 25 years, both approaches have moved from idealization to a
sense of the possible. The public sphere is being realigned. Taking e
xamples from France and Belgium, the author considers how religious in
stitutions-particularly Catholic ones-might find a new involvement, an
d identifies Islam as a catalyst for change.