Save for one year with a Unitarian church in Dorchester, Massachusetts, where he displeased his congregation by his opposition to slavery, he was not settled as a minister until 1853.
In 1853, he established an independent society in Lynn, Massachusetts, with which he remained till 1870, when he withdrew to complete studies of many years, the results of which appeared later in his publications.
The series represents what Johnson himself calls his “purely humanistic point of view.” It took its place among the most learned and liberal contributions to the study of comparative religion and civilisation.
His philosophy was highly transcendental; but being versed in many languages, he was acquainted with all schools, and with the results of history, literature, science and criticism in every department.
Scholars have compared his competence, patience and thoroughness in writing Oriental Religions with the same qualities in Darwin.