After studying Mods and Greats (classics with ancient history and philosophy) at Oxford, Nicholas turned to Patristics (early Christian writings) with a doctoral thesis on the church father Origen and his relations with the Jews. This led to a move to Cambridge and to Jewish studies. For many years he taught medieval Hebrew language and literature in the (then) Faculty of Oriental Studies (now FAMES), and Jewish religion and theology in the Faculty of Divinity. Among his better-known publications are Judaism (OUP), An Introduction to Judaism (CUP), Atlas of the Jewish World (Phaedon) and the Penguin Dictionary of Judaism.
At the same time he has pursued an interest in translating, mainly from modern Hebrew. His publications in this sphere include sixteen books by the late Amos Oz, with whom he worked closely. Recently he has turned his attention to possibly the greatest twentieth-century Hebrew writer, S. Yizhar.
Nicholas is a member of the Society of Authors and has chaired the Translators Association. He was elected a Fellow of the British Academy in 2011, and a Member of the Academia Europaea in 2013.