The demise of Christendom is of fundamental significance in understanding the present and future relationship between the churches and European culture. Attempts to develop post-Christendom perspectives are hindered by linguistic and conceptual confusion. This article explores misleading implications of the terms ‘post-Constantinian’ and ‘post-Christian’ and argues for the consistent use of the term ‘post-Christendom’. Use of the terms ‘Christendom’ and ‘post-Christendom’ has been criticised for failing to differentiate between different kinds of Church–state partnerships, some of which may be less problematic than others. This article acknowledges such historical differences but argues that there is an underlying ideological unity susceptible of being described and investigated under these labels. It argues further that attempts to promote a benign expression of Christendom as a possible future for Europe are unwise. It summarises the transitions occurring as Europe journeys beyond Christendom and argues for creative engagement with post-Christendom as an opportunity for ecclesial renewal.