The project examines the Christian Sunday’s shift from an originally religious holiday to an increasingly secular one. Focusing on the Sunday liturgy as a celebration of the Christian community the project aims at analysing its meaning for a plural society within Europe. Given the fact that the Catholic Church regards the Sunday as an important religious institution, changes in society mobilise ecclesiastical reactions. As a matter of fact, the Sunday liturgy constitutes the identity of the Christian community more than everything else. Thus it is important not only for the religious life of Christians but also for the plural societies within Europe. Four aspects show the importance of the Sunday in particular: 1. Official Church documents after 1965 emphasize the cultural identity of Europe and its implications for the Sunday. The experts offer hithero neglected points of discussion within the European societies. Two goals of the offical church become recognizable concerning the topic: the internal-church stabilization of Sunday and keeping Sunday as advantage of the society. The Christian Sunday is thought as a part of the cultural identity of Europe. The status of Sunday liturgy as paradigm of Christian life is moved thereby in the center. 2. Church organisations work strenuously for the preservation of the Sunday as a public holiday. As an example the survey analyses the work of the “German Catholics’ Foundation of St. Bonifatius” (Bonifatiuswerk der deutschen Katholiken) as one oft the biggest Church organizations and its promotion of the Sunday. This foundation is involved not only internal-church, but also exerts itself for a fair society. The charitable organisation informs all German parishes about possible actions to the preservation of Sunday as a work-free day which are often adressed explicitly to politicians. 3. Within liturgy the attention focuses on the so-called “purpose Sundays” (Zwecksonntage) which exist since the 1980s. They are assigned to a certain issue (e.g. family Sunday, media Sunday) and meant to bridge the gap between the secular sphere and the Church, between life and liturgy. 4. Liturgy emphasizes the importance of the Sunday for Christians and for the European societies. Therefore the theological importance of the feast as a means of constituting identity has to be highlighted at first. A new enhancement on the Sunday was promoted by the Liturgical movement at the beginning of the 20th century and by the Second Vaticanum. The efforts culminated in “Sacrosanctum Concilium” and are decisive for the importance of the Sunday. Finally the study will describe special liturgical practises in Germany, the Netherlands and France to compare liturgical theory and practise in order to emphasize the liturgical contribution to the cultural identity of Europe.