By Patrick Allitt, Emory University
In the early 20th century, the majority of Americans were Protestants, but a swelling immigration from Ireland, Italy, and Poland was bringing large numbers of Roman Catholics into America, while a Jewish population was also arriving from Germany (Reformed Jews) and from Russia, usually Orthodox Jews. Resultantly, soon, there were multiple homegrown religions as well.

Religious Pluralism
The American Catholic church was predominantly Irish in its ethnic character, but it became more ethnically diverse as the 19th century ended. A large Irish population had arrived in America after the potato famine of 1846 through 1848, and it was they who really created the major institutions of American Catholicism.
Jewish immigration also contributed to American religious diversity, and Jewish immigrants came, first, mainly from Germany. They tended to be already urbanized. And, they tended to have gone through a fairly high degree of assimilation into the mainstream of German society, and hence were fairly well adapted to make the switch to America, where they created and joined reformed synagogues.
American principles of religious freedom and church-state separation allowed everyone to flourish together, and soon showed doubters, especially the numerous anti-Catholics in America, that the nation could accommodate religious pluralism. As a result, America had some homegrown religions of its own.
This is a transcript from the video series A History of the United States, 2nd Edition. Watch it now, on Wondrium.
Mormons and Polygamy
One of the most famous homegrown religious group was the Mormons. It was founded in the early 1830s by Joseph Smith. After his assassination—his lynching in 1844—the second leader, Brigham Young, had led them out to Utah where they begun to pioneer in irrigation farming.
There was a famous Supreme Court case in 1879 called the Reynolds case. Reynolds was a Mormon who married two women, and was prosecuted for doing so, for violating the bigamy statutes.
He claimed that he had a First Amendment right; it was part of his freedom of religion. The Supreme Court wouldn’t have that, though. They said that he might be free to believe that plural marriage was right, but he was not free to act upon it.

Utah’s Statehood and Mormon Beliefs
Now, Utah wanted to become a state, but so long as the Mormons practiced plural marriage, the Union wasn’t going to admit them. Polygamy was regarded with absolute horror and dread by most of the vast majority of the American population.
Finally, a revelation to the new Mormon prophet, Wilford Woodruff, took place in 1890. In effect, God said to Woodruff that plural marriage is no longer necessary. Looking at it from a purely political point of view, it was clearly a quid pro quo: The Mormons gave up polygamy, and in return Utah gained its statehood.
Jehovah’s Witnesses End of the World
Another new American religion was the Jehovah’s Witnesses. Charles Taze Russell, a haberdasher from Allegheny, Pennsylvania, foresaw the end of the world, and he created the Jehovah’s Witnesses as a church dedicated to preparing for it.
He foresaw that the world was going to come to a catastrophic end in the year 1914. It was one of numerous millennial sects whose interpretations of biblical prophecy led them to see the world on a downward slope toward catastrophe.
Although the world didn’t end in 1914, the fact that that was the year when the First World War began enabled many of the Jehovah’s Witnesses to believe that it is the beginning of the end—that’s the view they held to through the 20th century.
Christian Scientists
A third new American religion was the Christian Scientists, founded by Mary Baker Eddy. It was an extraordinary religion, because its members denied the reality of the material world. They said, “What we think of as the material world is really a projection of our mental condition.”
It was an organization that denied the use of all kinds of stimulants, like tobacco, tea, and coffee. It also believed that one’s health was attributable to their state of mind. If you’re sick, it’s not because there’s anything really physically wrong with you, it’s because your frame of mind is wrong.
That’s why they also rejected all forms of medication. They believed that if your frame of mind is right, you won’t suffer, or you won’t become sick.
Christian Scientists on the Concept of Death
Mrs. Eddy herself apparently also believed that death itself was unnecessary, but, of course, as she reached extreme old age, she did, in fact, begin to sicken and approach death. She continued to say, “It’s not because I’m actually physically sick, it’s because my enemies are beaming malicious animal magnetism beams towards me. It’s they who are trying to overcome my frame of mind, and defeat it.”
It was popular in 19th century America, partly because orthodox medicine was so bad that quite often, you were as likely to recover by being left alone as you were by putting yourself in the hands of a doctor. Gradually, however, in the 20th century, as American medicine improved dramatically, the attractions of Christian Science commensurately diminished.
Common Questions about America’s Religious Diversity and the birth of Homegrown Religions
Mormons was one of America’s homegrown religious groups, founded in the early 1830s by Joseph Smith. After his assassination, the second leader, Brigham Young, had led them out to Utah where they begun to pioneer in irrigation farming.
Christian Scientists was a new religion founded by Mary Baker Eddy. It was an extraordinary religion, because its members denied the reality of the material world.
A haberdasher from Allegheny, Pennsylvania, named Charles Taze Russell, foresaw the end of the world, and he created the Jehovah’s Witnesses as a church dedicated to preparing for it. It was one of numerous millennial sects whose interpretations of biblical prophecy led them to see the world on a downward slope towards catastrophe.