The Agnosticism of Abraham Lincoln. By Lyman Abbott. The Outlook, November 17, 1906.
Lincoln's Faith. By John Hay. Address given from President Lincoln's pew in the New York Avenue Church, November 16, 1902. In John Hay's addresses.
The Religious Opinions and Life of Abraham Lincoln. By the Rev. William H. Bates, D.D., Washington, D. C., 1914.
Abraham Lincoln: A Lecture. By Robert G. Ingersoll. New York: C. P. Farrell, 1895.
The Religion of Abraham Lincoln. Correspondence between General Charles H. T. Collis and Colonel Robert G. Ingersoll. With Appendix, containing interesting anecdotes by Major-General Daniel E. Sickles and Hon. Oliver S. Munsell. New York: G. H. Dillingham Company, 1890.
Fifty Years in the Church of Rome. By Father Chiniquy. 42nd edition. Chicago: The Craig Press, 1892. Contains interesting account of Lincoln's service as Father Chiniquy's attorney and of interviews at the White House.
Abraham Lincoln: Was He a Christian? By James E. Remsburg. Extended chapter in "Six Historical Americans." New York: The Truth Seeker Co. Extended argument to prove that Lincoln was and continued to be an infidel.
Was Abraham Lincoln a Spiritualist? By Mrs. Nettie Colburn Maynard. Philadelphia: Rufus C. Hartranft, 1891. Contains extraordinary claims of revelations made to Lincoln while in the White House by a trance medium.
Sir Oliver Lodge Is Right: Spirit Communication a Fact. By Grace Garrett Durand. Privately printed, Lake Forest, Ill., 1917. Contains alleged revelations from Abraham Lincoln.
Abraham Lincoln a Practical Mystic. By Frances Grierson. New York: The John Lane Co., 1918.