In 1843, Dulon left the Prussian state Evangelical Church to become pastor for a German Reformed congregation in Magdeburg.

In November 1849 he protected the leftist Arnold Ruge, granting him church asylum from an impending arrest, and organised a further hiding place at Hermann Allmers's, before finding refuge in Brighton.

In 1850 he established the Bremen Tages-Chronik (Daily Chronicle), a social-democratic sheet - with Ruge contributing from abroad -, and Der Wecker.

Even in 1851, members of the Friends of the Light had complained to the senate, accusing him of denying essential articles of faith, mocking the gospel and open hostility to Christianity.

He became the pastor of an independent congregation in New York City, and at the same time issued a series of “Sabbath Leaves” in the interests of free religion.

Future Civil War general Franz Sigel, a Badensian, taught in Dr. Dulon's New York schools, and subsequently married one of his daughters.

[2] In the history of the Evangelical Church, there has hardly been another, except possibly Thomas Münzer, who has put religion in the service of revolutionary socialism so much as Rudolf Dulon.