The Seventh-day Adventist Church had its roots in the Millerite movement of the 1830s to the 1840s, during the period of the Second Great Awakening, and was officially founded in 1863. Prominent figures in the early church included Hiram Edson, Ellen G. White, her husband James Springer White, Joseph Bates, and J. N. Andrews. Over the ensuing decades the church expanded from its original base in New England to become an international organization. Significant developments such the reviews initiated by evangelicals Donald Barnhouse and Walter Martin, in the 20th century led to its recognition as a Christian denomination.

Foundations, 1798–1820s The Second Great Awakening, a revival movement in the United States, took place in the early 19th century. The Second Great Awakening was stimulated by the foundation of the many Bible Societies which sought to address the problem of a lack of affordable Bibles. The spread of Bibles allowed many who had not had one to be able to purchase and study it themselves rather than just hear it preached, and led to the establishment of many reform movements designed to remedy the evils of society before the anticipated Second Coming of Jesus Christ.Timothy L. Smith, Revivalism and Social Reform: American Protestantism on the Eve of the Civil War (1957) Many religious minority movements formed out of the Congregational, Presbyterian, and the Baptist and Methodist churches. Some of these movements held beliefs that would later be adopted by the Seventh-day Adventists.

An interest in prophecy was kindled among some Protestants groups following the arrest of Pope Pius VI in 1798 by the French General Louis Alexandre Berthier. Forerunners of the Adventist movement believed that this event marked the end of the 1260-day prophecy from the Book of Daniel.The Christian Guardian, 1830, Church of England Certain individuals began to look at the 2300 day prophecy found in Daniel 8:14. Interest in prophecy also found its way into the Roman Catholic church when an exiled Jesuit priest by the name of Manuel de Lacunza published a manuscript calling for renewed interest in the Second Coming of Christ. His publication created a stirring but was later condemned by Pope Leo XII in 1824.

As a result of a pursuit for religious freedom, many revivalists had set foot in the United States, aiming to avoid persecution.This information comes from Light Bearers by Schwarz and Greenleaf.

Millerite roots, 1831–1844

The Seventh-day Adventist Church formed out of the movement known today as the Millerites. In 1831, a Baptist convert, William Miller, was asked by a Baptist to preach in their church and he began to preach that the Second Advent of Jesus would occur somewhere between March 1843 and March 1844, based on his interpretation of . A following gathered around Miller that included many from the Baptist, Methodist, Presbyterian and Christian Connection churches. In the summer of 1844, some of Miller's followers promoted the date of October 22. They linked the cleansing of the sanctuary of Daniel 8:14 with the Jewish Day of Atonement, believed to be October 22 that year. By 1844, over 100,000 people were anticipating what Miller had called the "Blessed Hope". On October 22 many of the believers were up late into the night watching, waiting for Christ to return and found themselves bitterly disappointed when both sunset and midnight passed with their expectations unfulfilled. This event later became known as the Great Disappointment.

Pre-denominational years, 1844–1860

Edson and the Heavenly Sanctuary After the disappointment of October 22 many of Miller's followers were left upset and disillusioned. Most ceased to believe in the imminent return of Jesus. Some believed the date was incorrect. A few believed that the date was right but the event expected was wrong. This latter group developed into the Seventh-day Adventist Church. One of the Adventists, Hiram Edson (1806–1882) wrote "Our fondest hopes and expectations were blasted, and such a spirit of weeping came over us as I never experienced before. It seemed that the loss of all earthly friends could have been no comparison. We wept, and wept, till the day dawn." On the morning of October 23, Edson, who lived in Port Gibson, New York was passing through his grain field with a friend. He later recounted his experience:

We started, and while passing through a large field I was stopped about midway of the field. Heaven seemed opened to my view, and I saw distinctly and clearly that instead of our High Priest coming out of the Most Holy of the heavenly sanctuary to come to this earth on the tenth day of the seventh month, at the end of the 2300 days [calculated to be October 22, 1844], He for the first time entered on that day the second apartment of that sanctuary; and that He had a work to perform in the Most Holy before coming to the earth.

Edson shared his experience with many of the local Adventists who were greatly encouraged by his account. As a result, he began studying the bible with two of the other believers in the area, O. R. L. Crosier and Franklin B. Hahn, who published their findings in a paper called Day-Dawn. This paper explored the biblical parable of the Ten Virgins and attempted to explain why the bridegroom had tarried. The article also explored the concept of the day of atonement and what the authors called "our chronology of events".

The findings published by Crosier, Hahn and Edson led to a new understanding about the sanctuary in heaven. Their paper explained how there was a sanctuary in heaven, that Christ, the High Priest, was to cleanse. The believers understood this cleansing to be what the 2300 days in Daniel was referring to.

George Knight wrote, "Although originally the smallest of the post-Millerite groups, it came to see itself as the true successor of the once-powerful Millerite movement."Adventistreview.org. . This view was endorsed by Ellen White. However, Seeking a Sanctuary sees it more as an offshoot of the Millerite movement.

The "Sabbath and Shut Door" Adventists were disparate, but slowly emerged. Only Joseph Bates had had any prominence in the Millerite movement.Light Bearers, pp. 55–56.

Adventists see themselves as heirs of earlier outcast believers: Waldenses, Protestant Reformers including the Anabaptists, English and Scottish Puritans, Evangelicals of the 18th century including Methodists, Seventh Day Baptists, and others who rejected established church traditions.Arthur Patrick, Adventist Studies: An Annotated Introduction for Higher Degree Students.

Sabbath observance develops and unites

A young Seventh Day Baptist layperson named Rachel Oakes Preston living in New Hampshire was responsible for introducing Sabbath to the Millerite Adventists. Due to her influence, Frederick Wheeler, a local Methodist-Adventist preacher, began keeping the seventh day as Sabbath, probably in the early spring of 1844. Several members of the Washington, New Hampshire church he occasionally ministered to also followed his decision. These included William and Cyrus Farnsworth. T. M. Preble soon accepted it either from Wheeler or directly from Oakes. These events were shortly followed by the Great Disappointment.

Preble promoted Sabbath through the February 28, 1845 issue of the Hope of Israel. In March he published his Sabbath views in tract form. Although he returned to observing Sunday in the next few years, his writing convinced Joseph Bates and J. N. Andrews. These men in turn convinced James and Ellen White, as well as Hiram Edson and hundreds of others.Material above summarised from Light Bearers to the Remnant

Bates proposed that a meeting should be organised between the believers in New Hampshire and Port Gibson. At this meeting, which occurred sometime in 1846 at Edson's farm, Edson and other Port Gibson believers readily accepted Sabbath and at the same time forged an alliance with Bates and two other folk from New Hampshire who later became very influential in the Adventist church, James and Ellen G. White. Between April 1848, and December 1850 twenty-two "Sabbath conferences" were held in New York and New England. These meetings were often seen as opportunities for leaders such as James White, Joseph Bates, Stephen Pierce and Hiram Edson to discuss and reach conclusions about doctrinal issues.

While initially it was believed that Sabbath started at 6 pm, by 1855 it was generally accepted that Sabbath begins at Friday sunset.

The Present Truth (see below) was largely devoted to Sabbath at first. J. N. Andrews was the first Adventist to write a book-length defense of Sabbath, first published in 1861.

Trinitarianism At the formation of the church in the 19th century, many of the Adventist leaders held to an antitrinitarian view, thanks to many antitrinitarian Christian Connexion ministers entering the former Millerite fold. Ellen G. White contributed to this discussion by helping to develop a landmark doctrine called "the personality of God." This doctrine asserts that God is a tangible being, having a form. In one of her earliest publications of a vision, Mrs. White recalled asking "Jesus if his Father had a form like himself; He said he had" (DayStar March 14, 1846, par. 1). Thus Mrs. White's doctrine of God does not mesh with the trinitarian creeds which teach that God is a formless triune being. Mrs. White classified the personality of God as one of "the old landmarks" of the Seventh-day Adventist faith (Ms62-1905.14). At the same time, her theology clearly developed over the decades and by the late 1890's and early 1900s she published that there are "three living persons of the heavenly trio" (Special Testimonies Series B07 pg 63). She referred to the Spirit as the "third person of the Godhead" (Desire of Ages pg 671) and a stenographer's report of one her sermons in the early 1900s refers to the Father, Son, and Spirit as the "three holiest beings" (see 21LtMs, Ms, 95, 1906 par. 29).

Woodrow Whidden notes that the Christology of Ellen White is "a bit problematic, but more evidently Trinitarian and Athanasian" (Arianism, Adventism and Methodism: The Healing of Trinitarian Teaching and Soteriology). Her Pneumatology is also a bit unclear because, while referring to the Spirit as the third person several times, she wrote statements of direct equivalence between the Spirit and Jesus Letter 66, April 10, 1894- par. 18; Ms 125, 1906, par.13; Southern Review Oct 25, 1898). She also wrote about the Spirit being God making Himself into a fountain of Divine influence, and It being His vital presence, power, breath, life, character of God or His Son (7T 273; ST, November 23, 1891; BEcho August 5, 1901, par. 4, etc,...). Ellen White's son, William White, stated that he "never clearly understood" his "mother's position in reference to the personality of the Holy Spirit" but concluded that "the Spirit without individuality was the representative of the Father and the Son throughout the universe, and it was through the Holy Spirit that they dwell in our hearts and make us one with the Father and with the Son." (W.C. White to H.C. Carr, April 30th 1935). Seventh-day Adventists today, in general, tend to believe that the Spirit is His own individual person but there is confusion as to whether or not the Spirit is a separate bodily personage like the Father and Son.