I'd like to expand on something I recently said in email to a couple of friends. This has specific reference to the Church of Rome, but it's applicable to some other denominations.
What makes a denomination orthodox? If a denomination "officially" has one or more orthodox creeds, does that make it orthodox?
For instance, Catholic apologists point to the Catechism to prove Rome's orthodoxy. Of course, from a classic Protestant standpoint, the orthodox positions in the Catechism are offset by the heterodox positions. So that appeal cuts both ways.
There is, however, another issue. Creeds don't believe anything. An affirmation of faith doesn't affirm anything. Creeds are inanimate objects. It takes a person to affirm (or disaffirm) a creed.
It's rational agents who assent, dissent, believe, or disbelieve. Orthodoxy isn't primarily a matter of what's on paper. The church isn't a piece of paper. The church isn't a bunch of words. The church is people. What people actually do, actually believe.
Strictly speaking, it's not creed that are orthodox or heterodox, but people. Creeds have no beliefs. Only people have beliefs. Beliefs are properties of personal agents, not sentences. Creeds refer to grace, but creeds have no grace. Only personal agents have grace.
If you wish to get technical about it, words and sentences are intrinsically meaningless. They are only meaningful because they are meaningful to a linguistic community.
Because human beings aren't telepathic, we can't directly communicate ideas. So we use the medium of the spoken or written word (or sign language, as need be). Language encodes ideas.
Suppose we bracket God's mind. Suppose the only minds were human minds. Suppose human minds suddenly ceased to exist. All the books would become meaningless at one stroke. Without minds to understand the words and sentences, they have no meaning. Books are mindless.
I think good creeds are a good thing. But by themselves, creeds are not an index to the orthodoxy of a denomination.