Not all rational arguments for the existence of God have been successfully refuted. Scholars must turn a blind eye toward this one in order to keep up the pretense.
We learn about God when he reveals himself to us. Joseph
Smith said that a man could learn more about God by being in his presence for five minutes, than by reading everything that the philosophers have ever written.
The Book of Mormon is the best evidence of God, and of Jesus Christ. It records the visit of Jesus Christ to the Nephites subsequent to his resurrection in Jerusalem. The Nephites saw the fulfillment of the prophetic signs of his birth, and death, and then they saw him descend from the heavens. The Nephites were isolated and lived on a different continent. They had no way - other than divine revelation - to know of the events occuring in Jerusalem. They could not have forged this. Joseph Smith, the translator of the Book of Mormon, could not have forged it either.
Joseph Smith was praying in his room, when an angel appeared to him. The angel introduced himself as Moroni, and told Joseph about a book that was buried in a hill near his farm. He told Joseph that he would be allowed to retrieve the book, if he remained faithful, and translate it into English with the gift and power of God. He was also told that his name would be had for good and evil among all men.
After meeting with the angel every year for four years, Joseph was allowed to remove the book and translate it. After the translation was complete, he was allowed to show the book to three witnesses; they saw the book and the angel Moroni, and heard the angel proclaim the translation to be correct. Several others were also allowed to see it and thumb through its pages. Their testimonies can be found in the preface to the Book of Mormon.
No natural theory can explain the Book of Mormon, or its translation. Natural theories of its origin are easily discounted when viewed in relation to the actual facts. If there was no angel, then why did so many people see him? If Joseph wrote the book, then how did he get a knowledge of ancient Hebrew literary forms like Chiasmus, or of obscure Hebrew names? He was a farm boy with a third-grade education. If there wasn't any real book with gold plates, then why did so many claim to have seen it and thumbed through its pages? None ever denied their testimonies, which can be found in the preface to the Book of Mormon. If the Book of Mormon is fiction, then how come archeologists can use it to follow Lehi’s journey in the desert, and find the same places that are described in detail in the Book of Mormon? And how can the Book of Mormon describe literally hundreds of facts that can be cooborated from the lives and history of the Mayan people?
“There is no point at all to the question: Who wrote the Book of Mormon? It would have been quite as impossible for the most learned man alive in 1830 to have written the book as it was for Joseph Smith. And whoever would account for the Book of Mormon by any theory suggested so far—save one—must completely rule out the first forty pages.” (P. 139.) Hugh Nibley, "Lehi in the Desert"