No — not in the sense the slogan means. Six Protestant theologians were admitted, from 1968, as observers of the Consilium’s work. The decisive fact is on the record: in an official reply of 25 February 1976, the Vatican stated that “the Protestant observers did not take part in the composition of the texts of the new Missal.” They watched; they did not write, vote, or author. Claims that Protestants “designed” or “wrote” the new Mass are not supported by the evidence, and are contradicted by the official record. We say that plainly.

We will also not publish the lists of names that circulate in polemical literature, because they are not securely sourced. “Six non-Catholic observers” is what the reliable record supports; anything more specific should wait on a primary source, not a forwarded list. Getting this right is part of taking the question seriously.

That said, be fair to the real concern underneath the exaggeration. Ecumenical sensitivity was an acknowledged factor in the reform, not a secret one. The reformers themselves spoke of easing what might be a “stumbling block” to the separated brethren (in the accurate, narrower sense of that phrase, not the distorted version that pins it on “the Protestants”). And the Offertory was genuinely rewritten away from the older, explicitly sacrificial “immaculate host… for my innumerable sins” language toward a Jewish-style blessing over “the bread we offer you.” The fact of that change is solid; its theological weight is what is debated.

So the honest formulation is sturdier than the myth: Protestants did not author the new Mass (the Vatican itself said so), but ecumenical concern shaped some of the choices, and a Catholic may reasonably ask whether a liturgy is the place to soften what once distinguished Catholic worship. That question stands on its own, and it does not need the false claim of Protestant authorship to be worth asking.