Popes John XXIII and Paul VI insisted VII was just pastoral.
..."It is clear, as the following extracts confirm, that neither did Pope John XXIII, who convoked the council,authorize the council to treat dogma nor did Pope Paul VI, who promulgated the documents of the council, intend them to be part of the essential Magisterium of the Church. Both regarded the council to be pastoral, not dogmatic, in nature, and therefore not part of the essential Magisterium of the Church.
Some have noted that the titles of two of the documents, Lumen Gentium (On the Church) and Dei Verbum (On divine revelation), are preceded by the word "dogmatic." Canonists have noted that the authority of a document is determined not by its mere title. Rather, the authority is determined by the intent of the pope who promulgated the document.
What conclusion, therefore, can be drawn about the authority of Vatican II? That, according to the two popes of the council, it was merely pastoral in nature and is not to be accorded the authority of the essential Magisterium of the Church. In holding that understanding, Catholics are simply obeying the words of the two popes themselves. Vatican II, therefore, as a pastoral council, has no dogmatic force and can be held to be imprudent or even in error, with no compromise to one's Catholic faith..."
http://www.traditio.com/tradlib/faq08.txt
Ecumenism = new doctrine
And therefore not true doctrine, and thus no more binding than any other fallible opinion. "For the holy Spirit was promised to the successors of Peter not so that they might, by his revelation, make known some new doctrine, but that, by his assistance, they might religiously guard and faithfully expound the revelation or deposit of faith transmitted by the apostles."
Although I'm not sure why anyone would give any credibility to what Paul VI or JXXIII may have said given they were the ones who foisted this horror on us, I do get that believing this was just "pastoral" in nature helps certain Catholics sleep better at night.