The starting point is the modern sacred building in the changing constellations of our society. More than almost any other type of building, modernist churches reflect the change in the concept of architecture in the 20th century in terms of construction, design and spatial concept. At the same time, they show the transformation of the church into a democratic, community-orientated institution. Today, however, they are under serious threat: despite their listed status, adapting them to modern standards is complex and expensive, while their use as places of worship is dwindling. Yet they have great potential as socially valuable spaces, especially in often peripheral urban locations. Under what conditions can they open up, prove their worth and be preserved today?