While preparing for his M.A. examination in 1879, he had a crisis of faith resulting from his inability to reconcile science with the religious beliefs he had grown up with. He initially found it impossible to see how any serious intellectual could also be religious. He did not find any satisfaction in agnosticism; however, and remained open to a solution to his intellectual problems that included belief in God. In the 1880s Grubb began to develop an interest in social concerns, even cutting back on his teaching in order to devote time to the study of economics and to public work. In keeping with his desire to reconcile faith with science, Grubb was among those who vocally and successfully opposed the adoption of the
Richmond Declaration by London Yearly Meeting in 1888. Soon after, as a result of his regular participation in meeting for worship, Grubb was officially recorded as a minister in the
Religious Society of Friends. At the time, he still did not feel he had a firm basis for his faith, but was confident that it would come with time. ==Major contributions==