He became widely known for his 1984 BBC series The Sea of Faith, where he explored the decline of religion and asked whether the Christian faith still had a place today. The series led to the creation of the Sea of Faith Network, which remains active.
A life Fellow of Emmanuel College, Cambridge, Cupitt lectured in philosophy for 30 years and was a key non-realist thinker. His ideas challenged traditional views of God, asserting that "talk of God in transcendent and metaphysical terms belongs to an intellectual epoch that has long since passed."
While his 1980 book Taking Leave of God raised questions about his own faith, he described himself as a “Christian Buddhist”.
Though he stopped officiating at public worship in the 1990s, Cupitt continued to influence debates on faith and religion, encouraging open discussion about God’s existence and the future of the Church.
Several colleagues and former pupils have taken to social media to pay their respects. Giles Fraser wrote on X: "He was a fearless fighter for truth and integrity, and was a huge personal support to me even as I got more conservative than him. A lovely man. May he rest in peace and rise in glory."
GildasUnbound also wrote: "Don Cupitt converted me. His TV series “Sea of Faith” was the first time I had experienced Christianity as having anything to do with intellectual rigour or credibility.Happily for me, as I told him some years later, he converted me to a belief in a real, transcendent and objective God (Who is no object). He had the decency to be very gracious with this disappointment.May he rest in peace, and rise in glory - and some surprise."