The Jews had a very good reasons for this golden calf and their gifts they offered to it!
There there was the Protestant revolt what is called the Reformation. Martin Luther and the others he inspired to break with Rome were not completely at fault. Politics and religions were inextricably tied together and secular rulers and kings used Martin Luther to break from the political shackles of the remnant of the Roman Empire now headed by the pope in Rome. It didn't help that corruption had entered the Church's clergy, liturgy and simony as it concerned the sacraments and indulgences exacerbated the reformers.
After Vatican I when papal infallibility was defined and dogmatized (it had always been a doctrine), the Old Catholics went into schism over it. They thought they knew better. I am sure at the beginning they thought they were carrying on the true traditions of the Church.
Then in the last century, I think, someone correct me, some of the Polish Catholics in the USA were not too happy with the primarily Irish Church in America. There may have been other reasons but they went into schism and formed the Polish National Catholic Church, not in union with Rome but with valid sacraments and priesthood.
After the Second Vatican Council a similar schismatic act occurred under Archbishop Lefebrve. He thought he knew better than Rome and in defiance of Pope John Paul II ordained bishops without papal approval. Thus he was excommunicated and the FSSXP soon evolved as a reform movement within the Church (as they claim) but clearly censured by the Church's magisterium first with excommunications of all the bishops (not the priests and laity) which Pope Benedict lifted. But the priests and bishops had and have a serious censure that of suspension a divinas. This is serious stuff.
The FSSXP have experienced division too and other groups have spun off from them claiming the same legitimacy as the FSSXP in terms of being in full communion with the true Church. It sounds like what Martin Luther wrought. Initially he simply saw himself upholding what Christ wanted for his Church but still as a Roman Catholic but all that cascaded into a full blown breach that then led other reformers as proud or more proud than Martin Luther to put forward even more sterile reforms and a hatred for Rome.
I suspect in 100 years the FSSXP will be just like the Old Catholics after Vatican I, insignificant and completely something different than what they at first intended to be.
As for me, I remain a papist even if I question this, that or the other. I just thank God I'm not the pope or a bishop. It's hard enough just being a plain old priest! In the end, it will all come out in the wash and we'll know which popes are in hell, which popes are saints (the currently unproclaimed ones) and where the Church took detours.
The Magisterium will be judged as will rank and file laity. Ireland and every local Church from the time of Christ to His second coming will be judged and the sheep and goats separated.
It will be a day of reckoning similar to what Moses would do on coming down from the mountain with the 10 Commandments only to find the Chosen People in a state of idolatry worshiping a golden calf.