How many creeds, councils and confessions must a man adhere to in order to proudly wear the "orthodox" label? The answer really is: it depends. We would all agree that you should at least be able to say, with conviction, that you agree to all that you find in the Nicene Creed of 325 A.D.
Of course, this same council prohibited kneeling, and declared that you could only be rightly baptized by an orthodox believer, and if the person who baptized you later became an heretic, your own baptism would be invalidated. Which is the soft way of saying, the councils were often pretty good at dealing with identifying heresy, but were often a little over-the-top in assessing their own authority.
So where do we draw the line. If you accept the Nicene Creed, but kneel during the litrugy - can you still claim to be orthodox? What about if the guy who baptized you turns into a modalist ten years from now?
What about the Council of Constantinople in 381. Are you still orthodox if you agree with the new improved Nicene Creed (sans anathema)? What about if you disagree with that famous third canon - that the bishop of Constantinople should be next in power to the bishop in Rome? What if you thought both should have equal authority, or perhaps have no special authority? Would you still be orthodox?
What about the council of Ephesus in 431. Are you still orthodox if you think calling Mary the mother of Christ is wrong? Must she always be referred to as the mother of God? What if this council anathemized you because you think that Jesus cast out demons by the finger of God (Holy Spirit) - are you still orthodox?
What about the council of Chacledon in 451. Are you still orthodox if you felt that a deaconess need not be at least 40 years of age, or that monks and nuns should be allowed to marry like everyone else?
These councils did a good job (generally) of identifying heresies - and I think when most of us think, of "orthodox" we aren't thinking of all the ecclesiastic debris that came along side this stuff (such as was mentioned above), though the faithful papist may disagree. Typically we reason that if we agree with the bulk of the creeds (inasmuch as they agree with scripture), and we agree that the heresies identified by these councils are in fact heresies (though -not- because these councils called them heresies - but rather because we draw from scripture the same conclusions these councils drew from scripture.
We dare not suggest that we begin discarding or neglecting church history! Good gravy no, we just don't exalt these things above scripture.
We all (at least on the evangelical side of the fence) tow-the-line, parroting with zeal that "there must be a balance!" - even if we haven't the first idea where that balance is supposed to be. Too many of us, I think, ignore church history altogether because we feel that all we really need to know is our bible. But in thinking that we forget that the people who fell into heresy weren't without scripture themselves - that these "heretics" were typically the well-read theologians of their day - not laymen, but presbyters and bishops - well respected and quite influential indeed. It behooves us therefore to reason that if these worthy men could go astray - then we must allow for the possibility that left to our own devices, even having a good grasp of scripture isn't necessarily any sort of guarantee that we will never err in our understanding. The wise man errs on the side of caution - which in this case means he doesn't toss out church history because he knows how to read the bible.
The point to all this is really is just to highlight the fact that the term "orthodox" (I apologize again to my papist friends) isn't as cut and dry as it might first appear. Some would suggest that unless you can write the WFC out in your own blood - from memory - you are not orthodox "enough" - while others think that if you can recite the gist of John 3:16 your plenty orthodox already.
I recall with morbid fascination the first time I realized that I held a belief that had been anathemized by one of the councils (justification by faith alone has been anathemized you know). When I saw that there was a real synod that met and anathemized me, and when I correctly reasoned that these people had exactly the same authority as any of the people in any of those other councils which had anathemized all the other heretics - well, let's just say that I gained a new perspective into how much shrift I ought to be giving to the term "orthodox."
It was then that I became satisfied with a label that perhaps is less than orthodox - I call it the "I am not a heretic, at least as far as I know..." label. It works for me, for now.
The bottom line today people is this: Don't toss tradition out the window just because you are an evangelical, and don't cling to it as though it were scripture. A whole lotta error has been identified already and can be easily avoided ever after if we are willing to learn a bit from our christian fathers. Tradition is very much like a Christian "Talmud" - there are some good things in it, but following it exclusively or with undue authority is going to lead you eventually away from scripture, away from truth - and chasing a label** instead of Christ.
**Now 100% Talmud Compliant