George Duffield was a leading nineteenth-century New School Presbyterian minister who bore the same name as his father and grandfather. His evolution from unconventional doctrinal leanings to more orthodox and standard ones typified the moderation on both sides which led to reunion with the Old School Presbyterians in 1870.

The Old School–New School controversy was a schism of the Presbyterian Church in the United States of America which took place in 1837 and lasted for over 20 years. The Old School, led by Charles Hodge of Princeton Theological Seminary, was more conservative theologically and did not support the revival movement. It called for traditional Calvinist orthodoxy as outlined in the Westminster standards.