A building is converted from its original use and repurposed, which may include reconstruction and expansion.
There are three different kinds of conversion:
From religious to secular use:
A religiously used building is profaned / deconsecrated / taken out of liturgical use in order to be used as profane space. In Germany, mainly churches are subjected to this process. They then are repurposed as nurseries, libraries, restaurants or apartments. This category entails a spectrum of different nuances of repurposing (e.g. repurposing without profaning the building, part conversions of one part of the church, while the other is still in liturgical use).
Religious use remains but religion/denomination changes:
A religiously used building is reused as building for another denomination or religion. Conversions from religious to religious use also happen mostly to churches in Germany. There are e.g. Protestant and Catholic church buildings that become gathering spaces for Free Churches or orthodox communities (by renting, selling etc.). Sometimes, churches can become mosques or synagogues.
From secular to religious use
Secular spaces are being converted for liturgical / religious use. For this purpose, the original building is rebuilt and liturgical elements of the respective denomination or religion are added. Many mosques and Free Churches in Germany repurposed secular buildings such as storage halls, schools, shop floors or apartments.