First of all, how could one who accepts the Nicene and Apostles’ Creed not be a Christian? I think that is something you should ask yourself.If those do not help clarify who is and who is not a Christian, what in the world does? This is the very purpose of creeds and confessions: to determine in a concise manner who is within and outside of the fold.One has to ask why, i.e. upon what pretense, Dave selects the creeds of those councils, and not the Tridentine creed?
If one is going to include "heretics" who do not accept the Tridentine creed, why not accept heretics who do not accept the Nicene creed? After all, from Rome's perspective, both Arians (who reject Nicaea) and the Reformed (who reject Trent) are "outside the fold" in the same sense. Trent is not less of an ecumenical council in Romanism, nor is its authority any less.
I understand that there are Christians out there who like to use one of those creeds as being a true definition of what is involved in being a Christian. That's because they think that the essential doctrines of the faith are captured in those creeds. That's not Rome's position - Rome doesn't permit people to differ over what Trent has said: if you deny Trent, you can't reasonably call yourself a Roman Catholic.
For a Roman Catholic to select the Nicene Creed or the Apostles' Creed as definitive of what it means to be a Christian is, at best, arbitrary. Trent and Nicaea are equally authoritative for a Romanist. Monothelitism (not condemned at Nicaea) is just dogmatically defined to be a heresy as Arianism. Iconoclasm is as strongly opposed as Monothelitism. And Trent's Canon IX on Justification defines Sola Fide to be as false as any other condemned teaching.
Unfortunately, a number of Christians fall for this sort of sophistry. They imagine that folks like Mr. Armstrong are recognizing them as true followers of Christ by calling them a Christian. You should have seen him squirm, though, when asked the simple question of whether he equated "Christian" and "saved." (he himself documented his own numerous attempts to evade the question on his own blog - link) This confusion is exacerbated by the fact that there are many folks within the Roman Catholic Church who do actually think that non-RCs are just on different paths to heaven: RC members who essentially adopt pluralism. Those two groups read Vatican II's comments "ecumenical" comments in radically different ways.
And which group reads Vatican II correctly?