SUMMARY: The Encyclical Gaudium et Spes is a point of departure for a reconstruction of the theological positions that, from the year 1950 onwards, have sought to give a theological sense to the new social situation in which Christianity lives. The revision of certain points of these theologies leads to the consideration of the developments in the social theory in respect of the process of secularisation. The Churches and theological reflection must take into ac­count these theories and the concrete situation in which they are present in order to « adapt » their language and their practices.