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.
Anderson's conversion to Catholicism in 1849 marked a significant turning point in his life, as he remained faithful to his new faith until the end. He was subsequently chosen for leadership roles within the church, including president of the Particular Council of New York in 1856 and head of the Supreme Council in 1860.