Rayleigh was an Anglican. Though he did not write about the relationship of science and religion, he retained a personal interest in spiritual matters. When his scientific papers were to be published in a collection by the Cambridge University Press, Strutt wanted to include a quotation from the Bible, but he was discouraged from doing so, as he later reported:
Still, he had his wish and the quotation was printed in the five-volume collection of scientific papers. In a letter to a family member, he wrote about his rejection of materialism and spoke of Jesus Christ as a moral teacher:
He held an interest in parapsychology and was an early member of the Society for Psychical Research (SPR). He was not convinced of spiritualism but remained open to the possibility of supernatural phenomena. Rayleigh was the president of the SPR in 1919. He gave a presidential address in the year of his death but did not come to any definite conclusions.