As a member of the Religious Society of Friends, Ferris was a proponent of the views of Elias Hicks, claiming "obedience to the light within" as sufficient for salvation, and publishing a debate with an evangelical minister which contributed to a schism in 1827.
[1] In 1839, Ferris was appointed to a committee of the Yearly Meetings of Friends of New York, Philadelphia and Baltimore, to investigate wrongdoings against the Seneca Indians.
Although the treaty he recommended was ultimately rejected by the Senate, he was successful in brokering a deal which resulted in about half their land being restored to them.
Ferris was particularly interested in preserving the history of Wilmington, devoting several years of his life to research, and studying the Swedish language to enable him to use the records of the Old Swedes Church.
In 1846 he published A History of the Original Settlements on the Delaware: From its Discovery by Hudson to the Colonization under William Penn.