A Catholic convert, Marcel disliked this label, but his meditations upon the central concepts of the Christian life have a characteristic existentialist flavour. His emphasis on the personal nature of ‘mystery’ as opposed to the external nature of mere problems has had some influence in religious circles. His works include Être et avoir (1935), trs. as Being and Having (1949), The Mystery of Being (1951), the transcription of his Gifford lectures at Aberdeen, and The Existentialist Background of Human Dignity (1963), the transcription of his William James lectures at Harvard.