I am aware that many might be unfamiliar with the terminology used in this blog. Others might not understand my definitions of these terms because in society they often have different meanings. Her I will give my definitions of these terms as I will use them.
1. Orthodox: Literally orthos, (straight or right) and Doxa (Opinion or teaching). Refers broadly to those who hold to the historic teachings of Christianity as opposed to the heterodox who either deny core Christian teaching or add new non-biblical doctrines to it.
2. Conservative: In Protestant Christianity It refers to those who hold to the historic Christian faith, and its Creeds, rooted in an inerrant scripture. It stands in opposition to Liberalism which rejects inerrancy and the creeds.
3. Fundamentalist: Difficult to define because It is defined in so many ways, often pejorative.
The term has its origins in "The Fundamentals", a series of essays written between 1910-15 .
These sought to determine what doctrines were central to the faith and what was matters about which there could be disagreement. This was in response to the growing Theological liberalism inspired by 19th century German Higher criticism. By this definition conservative and fundamentalism. are interchangeable. The term is also used to describe a Segment of Conservative Christianity that strongly advocates separation and in the opinion of its opponents adds standard of orthodoxy that do not flow from Sola Scriptura. For Example Bible Presbyterian Church which under the leadership of Carl McIntire broke from the Orthodox Presbyterian Church in 1937, over the issue of Total abstinence from alcohol which they favored, and Dispensational Eschatology. They made these issue standard of Orthodoxy. These issue plus support of views like King James Onlyism, Strict codes of dress, etc. often define Fundamentalism.
4. Reformed: Refers to those Churches who subscribe to the Calvinist wing of the Reformation.
Consistent Reformed Churches hold to the Reformation Solas and have a reformed Creed. These
are as diverse as Conservative Presbyterians, Dutch Reformed, 39 article subscribing Episcopals,
Conservative Congregationalist, Independent reformed Churches and Reformed Baptists .I hope that clears things up.