The political behaviour of national, state or dominant churches in Western Europe is being affected by European Union (EU) integration in two ways. First, supranational legislation – especially the harmonisation of fundamental citizen rights in policy areas such as education and employment – has led to the political privileges that these churches have traditionally enjoyed being challenged. While the Amsterdam Treaty protects the right of the individual citizen to freedom of religious expression, the EU is an inherently secular body with no mention of Christianity in any of its treaties or directives. Second, the transfer of power to Brussels has meant that the territorial political influence of national churches is no longer clear, in any case. These two factors combined give evidence to suggest that this changing policy environment is leading churches increasingly to adopt interest-group behaviour. Does ‘ever closer union’ inevitably mean a less certain – if not necessarily less influential – political role for Christian churches throughout Europe?