Recently someone asked me to recommend books that will help understand creeds and confessional statements. I mentioned Philip Schaff’s magisterial (but outdated) Creeds of Christendom. Here are three excellent sources for your consideration:
Creeds of the Churches: A Reader in Christian Doctrine from the Bible to the Present by John H. Leith (John Knox Press). I hope it is still in print. If not, I’m sure used copies are available at the usual outlets on line.
Christian Confessions: A Historical Introduction by Ted A. Campbell (Westminster John Knox Press). (This one isn’t a reader; Campbell explains the creeds and confessions without reproducing them wholely. This would be an excellent supplement to the above work.)
American Religious Creeds: An Essential Compendium of More Than 450 Statements of Belief and Doctrine (three volumes) edited by J. Gordon Melton (Triumph Books). This is, of course, the most exhaustive of the three works. It includes everything imaginable in terms of statements of belief (but limited to the U.S.) including everything from Roman Catholic to The Theosophical Society (and everything in between). I believe this is out of print, but I bought my copies at used book outlets on line.
With these three works plus “Schaff” you have everything you could possibly need to understand Christian creeds and confessional statements.