Historically Whitehead's work has been most influential in the field of American progressive theology. The most important early proponent of Whitehead's thought in a theological context was Charles Hartshorne, who spent a semester at Harvard as Whitehead's teaching assistant in 1925, and is widely credited with developing Whitehead's process philosophy into a full-blown process theology. Other notable process theologians include John B. Cobb, Jr., David Ray Griffin, Marjorie Hewitt Suchocki, C. Robert Mesle, Roland Faber, and Catherine Keller.
What advancement of Whitehead's process philosophy is not attributed to Charles Hartshorne?