Christian's research interests comprise the histories of nations, regions and cities, mainly in relation to diverse forms of memory and identity politics across the Western world during the second half of the twentieth century.

He is particularly interested in ideologies instrinsic to historical controversies (especially nationalism), processes of deindustrialisation (especially actions for heritagisation), and social movements (especially the urban movements of the 'long 1970s').

His methodological repertoire is diverse, ranging from global comparison to biography. He has strong affinities with interdisciplinary scholarship such as historical sociology.

Prior to his employment at Utrecht he worked at the Institute for Social Movements (Ruhr University Bochum), and taught at the Humboldt University of Berlin as well as the Australian National University, where he obtained his PhD.

He has also held fellowships, for example, at the University of Edinburgh, Monash University, Federation University, the University of Sao Paulo, Dresden University of Technology and the German Historical Institute in Rome.