This 296-page 1903 book, now available on Project Gutenberg, presents a debate originally published in the Improvement Era between B. H. Roberts and the Catholic Rev. Van Der Donckt regarding the titular subject, along with some related material. As the editors of the Improvement Era wrote:

In the first two numbers of the present volume of the Era, an article on the Characteristics of the Deity from a ‘Mormon’ View Point, appeared from the pen of Elder B. H. Roberts. It was natural that ministers of the Christian denominations should differ from the views there expressed. Shortly after its appearance, a communication was received from Reverend Van Der Donckt, of the Catholic church, of Pocatello, Idaho, asking that a reply which he had written might be printed in the Era. His article is a splendid exposition of the generally accepted Christian views of God, well written and to the point, and which we think will be read with pleasure by all who are interested in the subject. We must, of course, dissent from many of the deductions with which we cannot at all agree, but we think the presentation of the argument from the other side will be of value to the Elders who go forth to preach the Gospel, as showing them what they must meet on this subject. It is therefore presented in full; the Era, of course, reserving the right to print any reply that may be deemed necessary.—Editors.

Roberts in fact wrote a lengthy reply. The original Roberts article, Rev. Van Der Donckt’s rebuttal, and Roberts’ reply form chapters one, two, and three, with a combined length of 170 pages. The balance of the book consists mostly of selected other discourses, including another lengthy Roberts lecture entitled “Jesus Christ: The Revelation of God”; extracts from Joseph Smith’s King Follett Sermon; and talks by Brigham Young, Orson Pratt, and Joseph F. Smith.

The debate, especially Roberts’ rebuttal of the ‘sectarian’ doctrine of deity, is the most interesting part of the work. He quotes scripture, philosophy, and ecclesiastical history (showing himself to be very well-read) to demonstrate the Greek origin and self-contradictory implications of the ‘sectarian’ doctrine and the merits of the ‘Mormon’ doctrine. He’s surprisingly candid and unashamed of the Gospel, espousing a belief in the “plurality of Gods” with confidence. An excerpt from Roberts’ reply to Mr. V (as he calls the Rev. Van Der Donckt) shows a bit of his engaging, adversarial style of debate:

After thus [in the preceding quote from Herbert Spencer’s “First Principles”] running to absurdity the prevalent conceptions of the “Infinite,” the “Absolute,” the “Uncaused,” Mr. V.’s “Most simple or not compound” “Being,” the churchman does what all orthodox Christians do, he commits a violence against all human understanding and good sense—he arbitrarily declares, in the face of his own inexorable logic and its inevitable deductions, that, “it is our duty to think of God as personal; and it is our duty to believe that he is infinite;” that is, it is our duty to think of the infinite as at once limited and unlimited; as finite and infinite—”which,” to use a phrase dear to Mr. Van Der Donckt, “is absurd,” and therefore not to be entertained.

The other discourses presented in the later part of the book serve to further flesh out the Mormon doctrine and demonstrate that it’s been uniform throughout the history of the Church. In summary, Mormon Doctrine of Deity offers a brilliant writer’s authoritative treatment of the topic, an engaging debate, and extracts from a who’s who of early Church leaders and thinkers. It’s well worth a read.