Because of his deep Christian faith, he was strongly opposed to slavery. In addition to supporting the Pennsylvania Abolition Society, he helped to create the African Methodist Episcopal Church in 1816. He encouraged people to read the Bible at home and study it in school; he believed that regular reading of the Scripture would advance the abolitionist cause.
He spent almost his entire life in and near the city of Philadelphia. Familiar with the countryside in southeastern Pennsylvania, he wrote:
A German farm may be distinguished from the farms of the other citizens of the state, by the superior size of their barns, the plain but compact form of their houses, the height of their inclosures, the extent of their orchards, the fertility of their fields, the luxuriance of their meadows, and a general appearance of plenty and neatness in everything that belonged to them.The high efficiency and productivity of the German farmers in Pennsylvania impressed Benjamin Rush. As a scientist, he valued the high yields they got from their land. Although his own heritage was largely English, he learned to appreciate the skills of the German farmers, and soon realized that they were necessary to keeping Pennsylvania economically strong.