Sherrard was a practising Eastern Orthodox Christian and was responsible, along with Kallistos Ware and G. E. H. Palmer, for the first full translation of the Philokalia into English.

He also wrote prolifically on theological and philosophical themes, describing what he believed to be a social and spiritual crisis occurring in the developed world, specifically modern attitudes towards the biophysical environment from a Christian and perennialist perspective.

His doctoral thesis on the Greek poets Solomos, Palamas, Cavafy, Angelos Sikelianos and Seferis (King's College, London) was published in 1956 as The Marble Threshing Floor.

In 1970 he accepted a lectureship on the history of the Orthodox Church, a post attached jointly to King's College, London and the School of Slavonic and East European Studies (SSEES).

In 1980, together with Keith Critchlow, Brian Keeble and the poet Kathleen Raine, he was one of the founding members of the journal Temenos, a review devoted to the "arts of the imagination".

Among his works (together with his collaborators Kallistos Ware and G. E. H. Palmer) is the complete translation of the Philokalia, a compendium of mystical writings by the spiritual fathers of the Orthodox Church.

This book is a collection of articles dealing with subjects such as tradition, death and dying, the problem of evil and the revival of contemplative hesychast spirituality.