Since the Revolution, America had become increasingly secular. Educated Americans, in particular, came to embrace the doctrines of the Enlightenment, which favored logic and reason over piety. Partly as a reaction against this growing rationalism, the Second Great Awakening emerged in the 1800s and caused a resurgence of religious faith.

Influenced by the Enlightenment ideals of logic and reason, many Americans began to question certain elements of the Christian faith, embracing new rational views on religion. Proponents of rationalism held that religious beliefs should not simply be accepted but should instead be acquired through investigation and reflection. For most rationalists, the existence of God was proven most prominently by the orderly workings of nature, which hinted at a rational creator. The most extreme rationalists, called Deists, argued that where the Bible conflicted with reason, it should be ignored. Deists, including Benjamin Franklin and Thomas Jefferson, believed that a rational God, like a celestial clockmaker, had created a perfect universe and then stepped back to let it operate according to natural laws.

Along with Deism, other rationalist challenges arose to traditional religion, including Universalism and Unitarianism. Universalism held that science and reason ensured that all souls would eternally progress toward salvation, regardless of the adoption of any specific creed. Between 1794 and 1807, Thomas Paine published his Universalist book, The Age of Reason, which objected to all organized religion. Many critics condemned this book as a defense of atheism. The other new creed, Unitarianism, opposed the Christian doctrine of the trinity (the belief that God exists in three equal and eternal parts: God the Father, God the Son, and God the Holy Spirit). Unitarianism gained a small following of religious liberals during the late eighteenth century, and grew throughout the early nineteenth century to emerge as a separate denomination with its own churches.

About seventy years after the First Great Awakening, the Second Great Awakening emerged during the early 1800s, partly as a backlash against the spread of rationalism, and partly in response to calls for an organized religion more accessible to the common man. As in the First Great Awakening, revivalist ministers during the Second Great Awakening urged followers to reach a personal, emotional understanding of God. Women, blacks, and Native Americans participated heavily in the revival meetings.

The revivals began in Connecticut in 1790. Unlike the revivals during the First Great Awakening, which were emotionally raucous and neared hysteria, these revivals were often calmer and quieter, as gatherers respectfully observed believers in prayer. In New England, these revivals spawned a movement to educate and reform America. Social activists, inspired by their renewed religious spirit, founded all sorts of evangelical and reform groups: the American Bible Society (1816), the Society for the Promotion of Temperance, abolition groups, and groups urging educational reform and women’s rights.

Religious fervor quickly spread to the West, where revivals more closely resembled the earlier, more animated revivals. In Kentucky and Tennessee, camp meetings were rowdy gatherings filled with dancing, singing, and shouting. The Methodists, who emphasized that religion was a matter of the heart rather an issue of logic, came to dominate frontier revivals. By 1845, Methodism was the most popular denomination of Protestantism in the U.S.

While the Second Great Awakening made great strides toward converting a secularized American public, it was not without critics. Some claimed the revivals encouraged more lust than salvation. Unitarians criticized the emotional displays of the revivals and argued that goodness sprang from gradual character building, not sudden emotional conversion.

Along with the Second Great Awakening, other religious reform movements arose in the nineteenth century to challenge rationalism. One such movement was transcendentalism, which emerged during the 1830s. Transcendentalists argued that knowledge did not come exclusively through the intellect, but also through the senses, intuition, and sudden insight. They believed that concepts such as God, freedom, and absolute truth were inborn and could be accessed through inner experience and emotional openness.

Two prominent transcendentalists were the authors Ralph Waldo Emerson and Henry David Thoreau, whose works emphasized spontaneous and vivid expression of emotion rather than logic and analysis. In his essays “Nature” and “Self-Reliance,” Ralph Waldo Emerson claimed that all people were capable of seeing the truth if they relied on their inner selves and trusted their hearts. In Walden, Henry David Thoreau recounted his two years spent living in a cabin in the woods away from civilization and materialism. He advocated living a simple life according to one’s conscience, not according to society’s repressive codes.

The Church of Jesus Christ of Latter-Day Saints, also known as Mormonism, was the most controversial challenge to traditional religion. Its founder, Joseph Smith, claimed that God and Jesus Christ appeared to him and directed him to a buried book of revelation. The Book of Mormon, similar in form and style to the Bible, tells of the descendents of a sixth century B.C.E. prophet whose family founded a civilization in South America. Violent religious persecution forced Mormons to move steadily westward in search of land upon which to establish a perfect spiritual community. After Smith’s murder in Illinois, a new leader, Brigham Young, led the Mormons to present-day Utah, where they have since prospered.