>>Protestantism is a heresy, Y/N?<<
No, a heresy is a false doctrine, or a movement to promote such a doctrine, proclaimed as authentic Catholic teaching. An apostasy is the withdrawal from the Catholic faith. Protestant "converts" are apostate, not heretical.
In one sense, "heretic" has a worse connotation, because it suggests the undermining of the true faith, but in another sense "apostate" is worse because it suggests the removal of oneself from grace, as opposed to mere error.
At the time of the COuncil of Trent, Protestantism could be largely identified as apostasy. Today, most Protestants simply have never been Catholic, and that term is also unsuitable.
I believe the shift in tone towards Protestants between Trent and Vatican II does not represent a change in doctrine, but a change in the denotation of "Protestant." At Trent, a protestant was an apostate. This is no longer true.
And to add to your theological correct post (Aw, come on, let us have a little fun, would you?), most Protestants born into their sects are "material" heretics, rather than "formal" heretics--but those who avidly reject Catholic teaching and call it the "whore of Babylon" and "the anti-Christ" are more likely formal heretics and schismatics.
Heresy is a denial of any of the truths contained in Christ's doctrine; Protestantism denies several of these, therefore the term is applicable and wholly appropriate. On an individual basis, all Protestants are material heretics; the formality of the heresy is determined by the culpability of the one professing the false doctrines.
You are incorrect. Apostasy means the total rejection of Christianity in favor of atheism, agnosticism, or paganism.
Like the denial of the Perpetual Virginity of Mary? Or the denial of the actual Presence of the Lord in the accidents of the Lord's Table?