Reformed confessions

For the most part, Reformed Confessions are in agreement, even where they have (compatible) differences. Of course there are differences like Baptism, the Lord's Supper, between Reformed Confessions and Calvinistic Baptist Confessions, that are incompatible. However, there is an organic unity if I may use that phrase between the confessions, and there are a great many of them, more than I am aware of, can keep track of, remember. I am always learning more about them. Awhile back, I learned that John Calvin wrote what is known as the "French Confession", and he "peer reviewed" the Belgic Confession. To further validate the claim of "organic unity", many Reformed Churches in Europe were united by the "Three Forms of Unity" consisting of the Belgic Confession, Heidelberg Confession, and the Canons of Dordt. The RCUS uses the Three Forms of Unity with the Apostle's Creed, Nicene Creed, and Athanasian Creed included in their book of doctrinal standards.

Oh, and this tadbit of information might be helpful, the Westminster Confession has undergone a couple of revisions, which caused quite a stir.

I recommend this resource to help flesh out some of the major ones: Reformed Confessions Harmonized: Various Authors - Paperback, Book | Ligonier Ministries Store