Seventh-day Adventist Church
The Seventh-Day Adventist Church is a Protestant denomination founded in America the mid-19th century during the Second Great Awakening. The basic tenets of Adventism were based on a version of premillennial evangelical Protestantism and focused on the prophecy that Christ would return in 1844. They also strongly held the belief that the [[Sabbath was Saturday (the 7th day), so they opposed laws making Sunday the Sabbath.
The church was organized in 1863 around the belief that Jesus indeed had entered the most holy place of the heavenly sanctuary in 1844. Ellen G. White (1827-1915), while holding no official role, was the dominant personality and moved the denomination to a concentration on missionary and medical work. Beginning in the 1890s, the Seventh-day Adventist Church was impacted by the Holiness Movement. Borrowing from the holiness movement, Albion Fox Ballenger and Sarepta M. I. Henry sought to bring together law and gospel themes, and thereby fill a spiritual need not met by Adventist emphasis on moral behavior. Revival focused on being filled with the Holy Spirit and healing. Mission and medical work continues to play a central role in the 21st century.
The church professes 28 fundamental beliefs which it sees as being based on the Bible, and which it states is the only basis of its faith, though historically it has privileged the teaching of Mrs White. Healthy food is part of the religion. Most Adventists are vegetarians, and reject caffeine and alcohol. Adventists in Battle Creek, Michigan, developed America's breakfast cereal industry.
Adventist missionary activity has been quite successful, and over 90% of members are outside the U.S., including 34% in Africa, 33% in Latin American, versus 8% in the U.S. and Canada. There is a very active missionary program in 230 countries. There are 15 million members, with the greatest numbers in Brazil (1.3 million); the US (950,000); India (920,000); the Philippines (750,000); Peru (660,000); Mexico (550,000); and Kenya (530,000). There are 64,000 churches and 16,000 ordained ministers. 
Worldwide the church operates 107 colleges and medical schools, and 7300 elementary and secondary schools. Total enrollment is 1.5 million. It operates over 700 hospitals, sanitaria and clinics. The worldwide budget is $2.7 billion, with $420 million spent on aid and relief efforts.
Origins in Millerism
The Second Great Awakening saw a general revival of evangelical Christianity, and was especially strong among Yankee Protestants in the "Burned Over" district of upstate New York. William Miller was a Baptist Minister who earnestly looked forward to the return of Christ, but who become inordinately consumed with determining the date. In 1831 he announced he had dated the Second Coming to 1843, when the world would end in a fiery purge. A recalculation moved the date to October 22, 1844.
A day after the failed prediction of October 22, 1844, a solution was provided for the problem by an Adventist named Hiram Edson. He argued that Miller misunderstood the nature of the predicted event, that it was not Christ's return to earth, but His entering in the holy of holies of the Heavenly temple, marking the beginning of the second phase of Christ's atoning work. This teaching was what would later become the SDA doctrine of Investigative Judgment, for which Heb. 9 in invoked, in which Seventh Day Adventism holds that Jesus began determining who among the forgiven was redeemed. (cf. 2Tim. 2:19) The chief proponent of this idea was Mrs. Ellen G. White. White, a woman of little education who reported she received prophetic visions and teachings from God, is considered to be the real founder. At that time, most Christians were opposed to women holding positions of church leadership.
Those who did not abandon Millerite Adventism concluded that God had indeed purged the heavenly sanctuary but did not appear on earth due to the sinfulness of humankind. The years of the Great Disappointment, 1843 and again in 1844, might have been the end of the Adventism movement. Instead, it was the beginning. True, Miller lost his audience but many believers soon found a new leadership in Ellen G. White (1827-1915). By 1863, this group had a new headquarters (Battle Creek, Michigan) and an official new name: Seventh-day Adventists. The national headquarters was later moved to Maryland.
Until 1870 the church had a "shut door" policy focused on veterans of the 1844 experience, seeing them as a saving remnant. The membership was only 5,400 and the door was shut to new members. Under White's guidance the denomination in the 1870s turned to missionary work and revivals, tripling its membership to 16,000 by 1880; rapid growth continued, with 75,000 members in 1901. By this time operated two colleges, a medical school, a dozen academies, 27 hospitals, and 13 publishing houses.
The Adventists had closely followed American politics, matching current events to the predictions in the Bible. They were alienated and hostile, for the government tolerated slavery and seemed to have lost its pure republicanism. Their magazines showed the U.S. government as an ugly monster. Under White's guidance the alienation softened. Adventists by the 1890s believed that the government might become a dangerous beast (as depicted in Revelation chapter 13), but had not reached that stage yet. The graphic images of government now depicted a friendly looking American buffalo.
The Seventh Day
"Seventh-day" means the observance of the original Sabbath, Saturday, is still a sacred obligation. Adventists argued that just as the rest of the Ten Commandments had not been revised, so also the injunction to "remember the Sabbath day to keep it holy" remained in full force. But this theological point turned the young group into a powerful force for religious liberty. Growing into its full stature in the late nineteenth and early twentieth centuries, these Adventists opposed Sunday laws on every side. Many were arrested for working on Sunday. In fighting against the real threat of a legally established National Day of worship, these Sabbatarians had to fight for their liberty on a daily basis. Soon, they were fighting for religious liberty on a broader, less parochial basis.
The fear that other Protestants would establish a Christian Sunday expanded into opposition to the establishment of a "Christian" identity for the nation, and opposition to school prayer. This led to alliances with secularists in the American political spectrum.
Adventist emphasis on health and healing coincided with broader emphases on proper diet, nonsmoking, and temperance--which usually meant abstinence. From Kellogg's Corn Flakes (an Adventist innovation) to sanitaria emphasizing natural cures to first-rate nursing and medical schools, as well as medical missions around the world, Adventists formed many alliances with more innovative forces, both secular and religious.
In the 20th century premillennial fundamentalism and political conservatism are often associated with each other. The premillennialism of Seventh-day Adventists, however, has not shared the outlook of that conservatism. The Adventists' views on race, prohibition, religious pluralism, the observance of the Sabbath (in the context of establishing Sunday as a national day of rest), and other matters exhibit similarities and differences when compared to the views of premillennial fundamentalists. Adventists have wanted to keep America Protestant, but they stressed liberty as the essence of Protestantism and thus helped to expand American religious pluralism.
At the end of World War II, the church reported 226,000 members in the US and Canada, and 380,000 elsewhere; the budget was $29 million and enrollemnt in church schools was 40,000.
Advent of Christ
Just because Christ did not return to earth in the 1840s did not mean that his return was not imminent, the Adventists argue, nor did it mean that preparations for that return should not remain uppermost in the minds and hearts of Seventh-day Adventists. Adventism is still the essential element in the identity of the group.
The major doctrinal conflicts that troubled the movement throughout the last third of the twentieth century include disputes over the nature of Ellen White's inspiration and authority, challenges to orthodox Adventist interpretations of Daniel 8, and debates over the role of good works in salvation. As with many doctrinal crises among evangelical Protestant churches, these conflicts often arose in disputes between the church's academics, increasingly trained in secular academic traditions, and its more theologically conservative, even reactionary, clerical administrators. In each case these controversies revealed an ambivalence by Adventists toward other Christians and secular society. They asked, are we like them or different, and how much does it matter? It was a crisis of identity for the church.
Role of women
Although the denomination was formed by a woman at a time women were not generally allowed in pulpits, the Adventists reversed policy at the same time most denominations became more accepting of women leaders. When Adventists wanted to emphasize their separation from the world, they denounced the gender roles of the larger society, and when they de-emphasized separatism and moved toward accommodation, they advocated gender norms, behaviors, and expectations similar to those of Fundamentalists.
Many Evangelicals in the 21th century denounce SDA as an illegitimate cult. 
- Edwards, Calvin W. and Gary Land. Seeker After Light: A F Ballenger, Adventism, and American Christianity. (2000). 240pp online review
- Land, Gary. "At the Edges of Holiness: Seventh-Day Adventism Receives the Holy Ghost, 1892-1900." Fides et Historia 2001 33(2): 13-30
- Morgan, Douglas. Adventism and the American Republic: The Public Involvement of a Major Apocalyptic Movement. (2001). 269 pp.
- Morgan, Douglas. "Adventism, Apocalyptic, and the Cause of Liberty," Church History, Vol. 63, No. 2 (Jun., 1994), pp. 235-249 in JSTOR
- Neufield, Don F. ed. Seventh-Day Adventist Encyclopedia (10 vol 1976), official publication
- Pearson, Michael. Millennial Dreams and Moral Dilemmas: Seventh-day Adventism and Contemporary Ethics. (1990, 1998) excerpt and text search, looks at issues of marriage, abortion, homosexuality
- Schwarz, Richard. Light Bearers: A History of the Seventh-day Adventist Church (3rd ed. 2000), official history
- Vance, Laura L. Seventh-day Adventism Crisis: Gender and Sectarian Change in an Emerging Religion. (1999). 261 pp.