The American-born Church of Jesus Christ of Latter-day Saints was on the threshold, Stark wrote, of becoming "the first major faith to appear on Earth since the Prophet Mohammed rode out of the desert."
In recent years, however, other scholars have noted a declining growth rate and lack of convert retention. They have even argued that the LDS Church doesn't have what it takes to be a world religion.
At an April conference sponsored jointly by Brigham Young University and the Library of Congress, British scholar Douglas Davies distinguished between "global religions," which have members in many different countries but never become part of the host culture, and "world religions," makes themselves at home in myriad places and cultures.
By these definitions, Buddhism, Christianity and Islam are world religions, while Judaism, Sikhism, perhaps Hinduism and Mormonism are global faiths.
Such distinctions are helpful but inadequate to explain a faith like Mormonism, historian Jan Shipps told a packed audience at the annual Sunstone Symposium at the Sheraton City Centre Hotel in downtown Salt Lake City. Shipps uses a new category - religious tradition.
Religious traditions must come into existence, be fully realized and firmly grounded in the real world before they can move on to become either global or world religions, she argued in her first book, Mormonism: The Story of a New Religious Tradition.
Shipps looked at six dimensions of religion in existing traditions like Christianity and Judaism - mythological, doctrinal, ritual, social/institutional, ethical and experiential - and concluded that Mormonism's distinctive features put it in that category.
The Book of Mormon, the church's unique Scripture, enriches the faith's mythological dimension, she said. Its doctrine develops through divine revelation, not human deliberations. The temple provides a ritual dimension; its lay clergy make the social/institutional aspects unique.
"The Mormon village lifestyle even in the urban areas of the great intermountain Mormon corridor made the everyday experience of the Saints unique," Shipps says. "The experiential dimension of religion in Mormonism was likewise unique."
Taken together, Mormonism is a new religious tradition, in a category somewhere between a world religion and a great world religion.
The best parallel, Shipps said, is Judaism that is "fully realized as a religious tradition but not able to be fully encultured in some parts of the world."
As it spreads across the earth, the LDS Church should beware of too much "triumphalism," though.
In the late 19th century, American Methodists thought Protestantism would soon be the Earth's dominant faith. It was spreading across the nation and sending masses of missionaries to foreign lands. They dubbed the era "the Christian Century," and believed that all the world would be Protestant before the passing of their generation.
"It was a heady time," said Shipps, a Methodist, and professor emeritus at the Indiana University/Purdue University at Bloomington.
By the early 20th century, Baptists had passed Methodists in number and their hopes were dashed.
"The Protestant mainline, and especially mainline Methodism, splintered as schism after schism rocked the churches," she said. "The 1960s saw the beginning of such numerical decline that the name 'Protestant mainline' is a historical curiosity that survives only because it has not been replaced with a better appellation."