He went on to work in a family business, Kesslers International Group, for 7 years before returning to his academic studies, completing a PhD degree at the University of Cambridge in 1999.

Kessler, with Martin Forward, founded the Centre for the Study of Jewish-Christian Relations (CJCR) in 1998[3] and was elected Fellow of St Edmund's College in 2002.

More recently his writings have focussed on the encounter with Islam and contemporary relations between the three Abrahamic faiths and implications for fostering a vibrant and open society.

At a lecture at the Brookings Institution in 2014, he argued that diplomats and policymakers need to be better trained in religion and belief, describing the contemporary religious landscape as a post-interfaith world.

In his 2024 address upo nreceiving the Seelisberg Prize at the University of Salzburg he called for a redoubling of efforts to pursue genuine dialogue at a time of increasing polarisation.

London and New York: Granta Publications 2010 – Introduction to Jewish-Christian Relations, Cambridge: Cambridge University Press 2013 – Jews, Christians and Muslims, London: SCM 2016 – Jesus, Stroud: The History Press 2024 - A Documentary History of Jewish-Christian Relations: From Antiquity to the Present Day, eds.

E. Kessler & N. Wenborn, Cambridge: Cambridge University Press (forthcoming) Kessler regularly appears in the media commenting on religion and belief issues of the day, such as the impact of October 7th 2023 attack on Israel and the Gaza War on the Leading Podcast, is a regular contributor to the Woolf Institute blog and hosted the weekly podcast Naked Reflections (2020-23).