[1] As a theologian Kelly was influenced initially by Charles Kingsley, but to more lasting effect by the writing of Frederick Denison Maurice, especially in his two volumes entitled The Moral and Metaphysical Philosophy and The Kingdom of Christ.
Although identified by others as Anglo-Catholic in his outlook, Kelly often stated that God and religion were not the same, challenging his own students to focus on issues of Faith and practical evangelism rather than the technicalities of church doctrine and administration.
While training people for missionary service in Korea and Africa, Kelly founded an Anglican religious order, the Society of the Sacred Mission, in Kennington, London in 1893.
Between 1913 and 1919 Kelly served at the invitation of the Society for the Propagation of the Gospel and the Bishops of the Nippon Sei Ko Kai as Professor of Apologetics at the Anglican Central Theological College, Tokyo, Japan.
[3] Kelly's influence on the development of the church in Japan was significant; a number of his students went on to leadership roles and helped to maintain the Nippon Sei Ko Kai's unique Anglican identification and independence through the political turmoil of the 1930s and Second World War.