Anderson converted to Catholicism in 1849; he was active in his new faith for the rest of his life. He was made president of the Particular Council of New York in 1856, and later the head of the Supreme Council in 1860.
In 1849, Anderson adopted Catholicism and remained committed to it for the remainder of his existence. He was subsequently chosen as president of the Particular Council of New York in 1856, and eventually rose to become the head of the Supreme Council in 1860.