Of the two polar groups representing dissent from Vatican II and the Holy See and the Holy Father in particular, in my most humble opinion, the ultra liberal, heterodox left is more sinister than the ultra conservative, ultra orthodox right when it comes to the corruption of the Church's faith, morals and unity.
For example, Archbishop Marcel Lefebvre is a dead hero to many and his community of the Fraternity of St. Pius X is a living sign of prophecy to the whole Church. The fact that the Vatican and the Pope have censured them, suspended their priests and excommunicated their bishops, but now lifted, it is fro them a a badge of courage being so bold as to buck Vatican II and the Holy See and the Holy Father.
On the progressive side of things, there are priests and religious who are challenging the Vatican and the pope about many things, such as the "pelvic" issues of ordination of women, marriage of homosexuals, use of artificial birth control and so on and so on.
There are a few heroes for the progressive side, like the now laicized former Maryknoll priest, Roy Bourgeois, living in Columbus Georgia and others like him.
What do these two groups have in common. They are neo-gnostics in the sense that they think their decision of conscience gives them an inside track that the authorities of the Church don't have, especially the pope and the bishops in union with him.
They also do something else that is very serious. They wound the unity of the Church and further fragment her.
I've said it before, and I'll say it again, in times like ours the best thing for any Roman Catholic is to follow the Holy Father and the bishops in union with him in the areas of faith and morals, or more specifically, Scripture, Tradition, Natural Law and Canon Law.
If you follow anyone else who teaches or suggests teachings in the areas of faith and morals that is contrary to the Tradition of the Church, then you've become a neo-Protestant IMO!
Fortunately the Holy See has a way of dealing with dissent and sometimes in the most patient ways. But make no mistake about it, the Holy See is the boundary keeper when it comes to dissent and heterodoxy. The Holy Father excommunicated the bishops of SSPX, but did not laicize them and by his charity he also lifted their excommunications.
Not so for Roy Bourgeois. He was dismissed from the Maryknoll Order mandated by the Holy See; He was excommunicated and now the Holy Father has laicized him.
It doesn't get more serious than that!