The doctrine of separation, also known as the doctrine of non-fellowship, is a belief among some Protestant religious groups that the members of a church should be separate from "the world" and not have association with those who are "of the world". There are many scriptures in both the Old Testament and New Testament of the Bible that provide the basis for this doctrine. For example:
Different groups vary widely in what to them constitutes separation. Additionally, there is a distinction between first and second degree separation. For example, many Christians want to live in a way that is distinct from the typical lifestyle of the world (first degree). This was supported by Dennis Costella when he said "We are in the world, but we are not to be a part of it." Others would claim that not only should one separate from the world, but also from those Christians who would not separate themselves from the world (second degree). Believers in second degree separation believe that Christians who are tied up with "the world" are themselves guilty of apostasy for their failure to adequately separate.
Practices and areas that should be separated under the more strict interpretations of the doctrine of separation include:
The doctrine of separation often leads to ecclesiastical separatism, in which Christians leave Christian denominations that they believe are apostate.