Baptists, unlike us Orthodox or other Protestant groups (such as Methodism) cannot trace their general group to one finder (some historians teach that John Smyth and Thomas Helwys, two Englishmen connected to the Separtist movement from the Church of England, gave this group it's general ideas, though). They disagreed with the Church of England on doctrines such as infant baptism, ecclesiastical authority, and church-state relations, among other things. Since the Sepratist movement was persecuted by the English government, Smyth exiled himself to the Netherlands and established the first Baptist church in 1609. Helwys, however stayed in England and started the first English Baptist church two years later. They both shared an Arminian theology, believing Christ died for all humans. Today, this is refered to as the General Baptists. Years later, though, the Particular Baptists emerged, who shared a more Calvinist theology. 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 lots of issues (such as practices and doctrines relating to church discipline and pacifism).
Another view is known as Landmarkism, which teaches that the first Baptists were the discples of St. John the Baptist. This,however, is extremely unlikely. The most notable denomination that holds this view is the American Baptists.
Since there are at least sixty-five Baptist bodies, it's hard to say exactly what they believe. Most put strong emphasis on the indepedence of the indiviual person and church and affirmation of believer's baptism (along with freedom of religion).
In Relation to Orthodoxy:
Orthodoxy disagrees with Baptists on:
authority Scripture infant baptism the nature of sin theosis
Baptists firmly believe in sola Scriptura (Scripture alone). Orthodoxy, however uses Holy Tradition to interpet the Bible.
Baptists don't recongnize the Greek Old Testament Books as Scripture (I'm not sure why this is so). Orthodoxy (as far as I know) does. (to be continued)
Note: This is my first article on this website. So don't be too critical