He opposed US military intervention in Russia during its civil war in favor of working with the new Soviet Union. During the 1920s, Davis returned to Russia several times and continued to advocate for Soviet cooperation. His chart of the construction of the Soviet government was published in "Workers' Dreadnought". By 1920, however, he had returned to the States, and finished his studies at the Union Theological Seminary. In 1922 he obtained a doctorate in sociology from Columbia University.