I've mentioned Rev. John T. Pressly's article on Church Fellowship in a couple of other places on this blog, but I wanted to make a more up-front recommendation of it. Rev. Pressly was a United Presbyterian minister, and the article was published in 1865. It is one of my favorite articles on the church, as it very clearly and succinctly articulates a biblical perspective regarding the adoption of creeds, the requirements of church membership, the error of latitudinarianism, the meaning of denominational separation, and the principles of church fellowship given the fact of denominational divisions. His clear articulations shed much light on these issues. I don't agree with everything he says, and some of his article focuses on some things peculiar to the United Presbyterian denomination of his time, but, overall, I think his article is enormously helpful in providing clarification on the principles of the unity and authority of the church and how to understand these things in an age of widespread denominational division.