These two books are both about the history of ecumenism from the later nineteenth century, but in most other respects they are completely different. Udi Greenberg’s work is a tightly argued monograph, while the book edited by Judith Becker and Dana Robert is a conference volume with no fewer than sixteen contributors drawn from several continents. Greenberg’s theme is the slow bridging of the gulf between Catholic and Protestant Churches between about 1880 and 1980, and he gives special attention to the 1930s and the 1960s. He does not discuss the differences within Protestantism. These, however, are the theme of the Becker–Robert volume, which concerns inner-Protestant ecumenism (‘the young ecumenical movement’) from the 1880s to the 1930s, giving special attention to the 1920s. Greenberg focuses not simply, as the title indicates, on Europe, but specifically on the German-, French- and Dutch-speaking countries of central and western Europe, making scarcely any mention of Britain, Ireland or Scandinavia. Contributors to the Becker–Robert volume, in contrast, range freely across North America, Europe and Asia; almost every country in those continents with significant numbers of Protestants receives some attention, and there is also a chapter on Madagascar.

Greenberg’s book is a history of ideas, and he draws on writings by an impressive body of theologians, polemicists and social-political thinkers who addressed the relations between Catholicism and Protestantism. His concern is with what he calls ‘Christian elites’, and he does not try to assess how widely the ideas that he describes were shared by Catholics and Protestants more generally. The same is largely true of the Becker–Robert volume, though a few of the contributors venture further towards the grassroots. The Becker–Robert team adopt a variety of approaches, but their volume is primarily a history of the many organisations which, from the 1840s onwards, were bringing Protestants from different denominations and different countries together.

Above all, there is a difference in tone between the two books. The Becker–Robert team tend to be sympathetic to ecumenism and, without being uncritical, they are often inclined to attribute idealistic motives to their protagonists. Greenberg is much more distanced, and frequently ready to attribute self-interested motives.

Greenberg’s central argument is that ecumenism initially developed as a defensive project, as Catholics and Protestants began to realise that their differences were less fundamental than the differences between Christians on the one side and socialists, feminists and Muslims on the other. He sees the key turning point as being the Nazi period in Germany. On the one hand, when the Nazis were still seeking Christian support, they argued that confessional differences were irrelevant and that Christians should unite against the common enemies of Judaism and Bolshevism. On the other hand, Christians hostile to Nazism were increasingly ready to work together against their common enemy. One could add that the experience of Nazi occupation also brought former foes together in other countries. The results were seen in what Greenberg calls ‘The Grand Compromises at the Zenith of Christian Power’ between 1945 and 1965. He sees Christian democracy and the unification of Europe as ecumenical projects, underpinned by anti-socialism, ‘an obsession with social hierarchies’ and efforts to ‘shore up patriarchy’. In summary, he identifies the Christian strategy as being to ‘insist on maintaining old hierarchies while making them more palatable, particularly for those assigned a lower position’ (pp. 212–13). But Greenberg’s previously acerbic tone is dropped in a final chapter, where he provides a more strictly descriptive account of ‘Radical ecumenism in the 1960s and ’70s’.

Contributors to the Becker–Robert volume show that, from the 1880s and ’90s onwards, international and interdenominational Protestant organisations, as well as personal contacts, multiplied. The already existing YMCA and YWCA became increasingly global, and new bodies such as the World Student Christian Federation were established. This process went much further in the 1920s, with the formation of the International Missionary Council, and the international conferences on Faith and Order and on Life and Work, which included Orthodox as well as Protestant participants. Some ecumenists were hopeful that Roman Catholics would also join them, but Pius XI in his 1928 encyclical Mortalium animos made it clear that this would not be permitted. While Greenberg sees ecumenism as being long propelled by a defensive and conservative agenda, the Becker–Robert team argue that ecumenism was driven by the more progressive sections of the various Churches, often strongly influenced by the social gospel. Ecumenism was also strongly promoted by Asian and African Christians, who were impatient of the denominational distinctions brought from Europe and North America. Above all, the contributors stress the enormous impetus both to ecumenism and to internationalism more generally given by the First World War, and the desperate need to ensure that nothing like it ever happened again. The connecting thread in the volume is the tension between these hopes and visions and the persistence of nationalist identities and loyalties.

Greenberg’s is a forcefully written and deeply researched book with an arresting thesis. My chief reservation concerns his tendency to overstate the degree of Christian consensus, and thus to exclude nuance. For example, he tends to treat ‘socialism’ and ‘communism’ as interchangeable, so that, when Emil Brunner condemns the communist assault on democracy and on religion, he is said to be condemning ‘socialism’. And while noting that German Christian democracy was conceived as an ecumenical project, Greenberg does not mention the Christian Democratic Union’s increasingly Catholic character and the reconciliation in the 1950s between German Protestants and the Social Democrats. The strengths of the Becker–Robert volume are of the opposite kind. It inevitably lacks the coherence of Greenberg’s work, but the contributions are equally well researched and they are without the polemics. They convey more of what might be called ‘lived ecumenism’, whether through studies of key individuals or through the practical ecumenism of the anglophone armies of the First World War, with their friendly co-operation between Catholic and Protestant chaplains. And, while Greenberg analyses the strategies of Western missionaries, the Becker–Robert team give equal attention to the perspectives of Indian, Chinese, Japanese, Korean, Arab and Malagasy Christians.