Although the oikumene is the whole inhabited world, the term Ecumenism has been appropriated to relations between Christians. Therefore Fr Eugene Hillman, treating of non-Christian relations with the Church, had to qualify it as The Wider Ecumenism in the title of his new book, which develops previous writings of his.

The relaxation of obstacles, largely legal, to relations of Catholics with other Christians has resulted in a short time in widespread changes of attitudes. These, in their turn, are exerting pressures on theology to review old positions, for ecumenical charity finds certain apparently established views incompatible with its experiences. Of such a nature seem to be the calls to revise the theology of the validity of orders, and of intercommunion.

In the case of the wider ecumenism with non-Christians, the obstacles have been more theological, and, indeed, due largely to a lack of any theology of other religions. The elements of such a theology are to be found in tradition, and in recent years it has been developing in academic circles, especially in Germany. But so far these developments have had little impact on those who live and work in non-Christian places, where the old views and the consequent attitudes persist, with increasing tension being felt by Catholics and all Christians between them and the signs of the times.