As early as 1836, Thiersch had become interested in the Catholic Apostolic Church ("Irvingism"). In 1847 he converted, and in 1850 resigned his professorship to dedicate himself as a minister in that church.
As early as 1836, Thiersch had begun to take an interest in the Catholic Apostolic Church ("Irvingism"). In 1847 he made a change of heart and converted, subsequently relinquishing his professorship in order to devote himself fully as a minister within that church.