In his highly interesting book The American Religion (1993), Harold Bloom (himself perhaps the most famous US literary critic of the past several decades) famously described Joseph Smith (1805-1844; 'the Mormon Prophet') as an authentic religious genius.
But, although this comment showed that Bloom had understood the magnitude of Smith's achievement, this was something of a back-handed compliment!
Because Bloom did not, of course, believe that Joseph Smith was an authentically-inspired prophet - and therefore (given the scope of JS's achievement) Bloom was stating what must therefore be the case: that Joseph Smith was a genius in having himself created a remarkable new religion.
(In passing, it is worth noting that Bloom, a Jew, clearly found the earlier and more Hebraic, Old Testament, millennial, Zion-building style of theocratic Mormonism more remarkable - and, one senses, more congenial - than what Mormonism became after polygamy was abolished and Deseret/ Utah joined the United States and was fully subjected to Federal government and laws.)
So what was Joseph Smith's achievement such that Bloom (something of an expert on geniuses) called him an authentic genius?
1. Writing The Book of Mormon in a few months (plus associated scriptures and revelations).
2. Creating an entirely new Christian theology (what he termed the 'restored' Gospel).
3. Founding an extremely successful church - its distinctive priesthood, offices, rituals, and organization.
In fact Smith's achievement was made even more extraordinary by his further innovation -
4. An explicit acknowledgement of his own fallibility and limitations; such that the church incorporated the expectation of continuous revelation and revision of the scriptures, theology and church organization.
This meant, in effect, that JS trusted his created forms actually to improve on what he had done.
And such was a pretty unusual, perhaps unique, trait among the founders of major religions.
So, if Joseph Smith is not regarded as an inspired Prophet, then he must indeed have been a genius; someone combining scripture-writing abilities approximately equal to an author of one of the minor books of the Old Testament, with something close to the theological creativity and comprehensiveness of St Paul, and the church-organizing abilities of St Peter...
On the other hand, a close examination of the life and character of Joseph Smith does not seem to reveal the personality or abilities of that kind of genius...
Most people who are not themselves Mormons do not recognize the scope and magnitude of Joseph Smith achievement, simply because they do not know enough about the subject.
For them there is 'nothing to explain'; and (like most of JS's contemporaries - and Mormonism was born and grew under the intense skeptical, mocking and aggressive scrutiny from the mass media and existing churches) Smith can be written off as merely a 'lucky' fool (lucky, that is, apart from being tortured, imprisoned and murdered) and/ or a cunning fraud (perhaps covertly motivated by seeking a harem).
But, if one is knowledgeable and honest enough to admit the astonishing achievement of Mormonism, then the more that can be said against Joseph Smith, the less likely it is that he really was 'a genius'; and therefore the more likely it is that he was just what he said he was: an inspired, but fallible, prophet.