Baptists are a variety of Evangelical Protestantism. Baptists claim 90 million members worldwide, approximately seventy percent of which reside in the United States.
Baptists cannot trace their denomination's beginnings to any one founder. Most reputable historians teach that John Smyth and Thomas Helwys, two Englishmen connected to the separatist movement from the Church of England, gave this group its general ideas, though. Smyth and Helwys disagreed with the Church of England on doctrines such as infant baptism (hence the name Baptist), ecclesiastical authority, and church-state relations, among other things. Since the separatist movement was persecuted by the English government, Smyth exiled himself to the Netherlands and established the first Baptist church there in 1609. Helwys, however, stayed in England and started the first English Baptist church two years later. Today, this schismatic group is referred to as the General Baptists. Years later, though, the Particular Baptists, who shared a more Calvinist theology, arose. They offically emerged in 1644 with their London Confession of Faith.
Some also believe the Baptists got their start from the Anabaptists. However, this is unlikely, due to the fact that Baptists and Anabaptists disagree on many issues (such as practices and doctrines relating to church discipline and pacifism).
Another view known as Landmarkism teaches that the first Baptists were the discples of St. John the Baptist. This, however, is extremely unlikely as Baptism espouses many doctrines that developed either in post-schism Catholicism or in other Protestant sects, more than a millennium after Christ. The most notable denomination that holds this view is the American Baptists.
Since there are at least sixty-five Baptist bodies with no structured ecclesiology, it's hard to precisely define their doctrines. Nevertheless, there are some points common to all Baptists. For example, most adherents place strong emphasis on the indepedence of the individual person ("individual soul liberty"), independence of the each church, affirmation of the believer's baptism, and distinctively American concepts such as freedom of religion and separation of church and state.
Orthodoxy disagrees with Baptists on:
Baptists are part of the "congregationalist" heresy, meaning that they don't have bishops or any traditional ecclesiological structures. Instead, Congregationalist church governance gives autonomy to individual local churches in areas of policy, polity and doctrine. Baptist churches are not under the direct administrative control of any other body, such as a national council, or a leader such as a bishop or pope. Administration, leadership and doctrine are usually decided democratically by the lay members of each individual church, which accounts for the variation of beliefs from one Baptist church to another. Such a system allows for each person to decide independently to believe whatever they wish, making it effectively impossible for a single Tradition or the One Holy Catholic and Apostolic Church to be preserved. Also, Baptists ascribe to a doctrine called the "priesthood of all believers." This notion states that every Christian has direct access to God and the truths found in the Bible, without the help of an aristocracy or hierarchy of priests. Thus priests are made into mere church leaders or financial managers, not the center of Christian life as the celebrants of the Divine Liturgy.
Baptists firmly believe in sola Scriptura (Scripture alone). Orthodoxy, however, uses Holy Tradition to interpret the Bible. Like all Protestants, Baptists reject the deuterocanonical book of the Old Testament, considering them to be less than divinely inspired. Biblical inerrancy is yet another common heresy among fundamentalist Baptists. Furthermore, the individual Baptist is free to interpret the Bible for himself, usually using "historical Biblical scholarship," which was pioneered in the late 19th century, while rejecting the previous two millennia of commentaries by the Holy Fathers.
Baptism, commonly referred to as believer's baptism among Baptists, is an ordinance that according to Baptist doctrine plays no role in salvation. That is, the act of baptism does not actually save a person or cleanse him from all his sins. Instead, it is merely an outward observance, properly performed only after salvation, which occurs when a person professes Jesus Christ as Lord and Savior. This completely opposes Orthodoxy, which regards baptism as a real supernatural transformation, through which the believer dies and rises again with Christ in a very real manner.
Through Anabaptist influence, Baptists reject the practice of pedobaptism, or infant baptism, because they believe parents cannot make a decision of salvation for an infant. Related to this doctrine is the disputed concept of an "age of accountability" when God determines that a mentally capable person is accountable for their sins and eligible for baptism. In contrast, reason and mental capacity are not essential factors in either Orthodox baptism or Holy Communion. This "tradition" arose from the legalistic, overly rationalistic theology of the Roman Catholic Church, which puts pure intellect above all else.
Baptists, like nearly all Protestants, hold a sola fide soteriology. This misinterpretation of Ephesians 2:8 states that a person must only willfully repent of sin, accept the substitutionary payment of his own sin by faith in Christ's death, and declares that Jesus is Lord in order to attain salvation. Any mention of the necessity of "works" such as fasting, prayer, or charity being necessary or even helpful for the soul are thus anathema to Protestants. Consequently, theosis is an alien concept to Baptists. Their theology leaves little or no room for improvement after conversion, much less an individual's struggle to free themselves from the passions and live an increasingly godly life. In Baptism, a healthy spiritual life is nothing but a nice postscript.