This study explores the interrelationship of pneumatology, eschatology and the Eucharist in the sophiology of Sergii Bulgakov (1871-1944) as a window into his rethinking of ecumenism. Bulgakov held, in his late theology and pastoral praxis, that only through the divided Christian churches reuniting eucharistically could the Spirit's work come to consummation, Christ return and the end of history come to completion with the divine and creaturely wisdoms (the two Sophias) being "reunited" so that 'God may be all in all' (1 Cor. 15:28). This was, above all, expressed in his quixotic June 1933 proposals for limited episcopally blessed intercommunion between the Anglican and Orthodox churches in the Fellowship of St Alban and St Sergius. The paper will explore the potential links between spiritual and sacramental renewal and the future of ecumenism through a historical and critical analysis of Bulgakov's thought. It will draw, in particular, on the author's co-founding in 2017 of the US based Orthodox-Pentecostal academic dialogue as well as his engagement with related Orthodox ecumenical encounters with Catholic, Anglican and Baptist traditions.