Wallace was raised in the Calvinist branch of Protestant Christianity, but showed an interest in other religious teachings during his life. He was deeply interested in religion from a young age, reading works by authors like Ralph Waldo Emerson, Ralph Waldo Trine, and William James, whose "The Varieties of Religious Experience" had a particularly strong impact on Wallace. After his grandfather's death in 1916, he left the Presbyterian Church and became increasingly interested in mysticism. He later said, "I know I am often called a mystic, and in the years following my leaving the United Presbyterian Church I was probably a practical mystic… I'd say I was a mystic in the sense that George Washington Carver was – who believed God was in everything and therefore, if you went to God, you could find the answers". Wallace began regularly attending meetings of the pantheistic Theosophical Society, and, in 1925, he helped organize the Des Moines parish of the Liberal Catholic Church. Wallace left the Liberal Catholic Church in 1930 and joined the Episcopal Church, but he continued to be interested in various mystic groups and individuals.