There’s no question that Vatican II was a Council of the Church, called by and presided over by the Pope and filled with bishops.
Therefore, it would be preserved from serious error or heresy by the Holy Ghost, as Jesus promised His Church.
But this is not to say that it was necessarily a smart move, or a needed council, or that everything that was done was an improvement in the Church. If you examine the history of Church Councils, some were of major importance, some are pretty much forgotten by all but historians, and some may even have moved things in the wrong direction, to be corrected later. But no heresies.
I think Vatican II certainly produced some very questionable results, even if many of those results were the product of dissidents and liberal heretics who twisted what the Council actually said to their own purposes. There is a big difference between Vatican II and the so-called “spirit of Vatican II” which those dissidents preached. But perhaps it could be argued that the Council was a mistake if it gave them that opportunity. Not heretical, and certainly not justifying splitting off from the Church, or individuals leaving the Church. But not producing the kind of good results that were expected when the Council was convened.
I have read all the documents of Vatican II, and I have not found any signs of heresy in them. Nor have those who criticize the Council ever successfully pointed out any specific examples that are convincingly heretical.
Presumably all those trouble-making bishops and priests and nuns and lay staff who shook up the Church after Vatican II would have found some other excuse to do much the same, in any case. They were already in the Church when the Council was convened. But the Church has gone through even worse crises in the past, most obviously the Manichean heresy which infected the majority of bishops, but has recovered from them by God’s grace. The Church will recover again.
Thanks for your insights. You addressed what troubled me in the article about heresies, and I thank you.
I'm not sure if I would recognize or even discern any sign of heresy. I admire your perseverance.
It IS amazing to me that in spite of all the errant popes that served over the ages, no heresy has ever reared its ugly head long enough to become part of the Church teaching. If that's not proof of the guidance of the Holy Spirit I don't know what is.