[TotusTuus]

If you deny that the Son is eternal (that he only became the "Son" at the Incarnation), are you legitimately a Trinitarian?

From the Catholic perspective? No.

St. Athanasius, a Catholic bishop whom the above creed is traditionally ascribed to (though he may not have in fact written it), fought this very heresy that you describe.

[Jean Chauvin]

Athanasius was the Bishop of Alexandria -and thus was on the same level of the Bishop of Rome (what you guys call the "pope"). In fact, some call him the Pope of Alexandria.

Of course, official Roman Catholic History tends to be at odds with reality, so I don't expect you to recognize these facts.

But, you were correct (inadvertantly) in calling him a 'catholic' biship. While he certainly wasn't 'Roman' catholic, he was a member of the catholic (universal) church, after all. He just happened to be the head of the Alexandria branch.

Jean