From Church Militant: SSPX poachers. The SSPX has a habit of luring the faithful away from diocesan-approved Traditional Latin Masses.
I sought out and went to the SSPX for a year in the '80s when there was no diocesan-approved traditional Latin Mass. They do much good, often being the only kind of Catholic orthodoxy in their area, and we have the old Mass back in the official church thanks to them. (That is, thanks to church authorities reacting to them.) The article is essentially right (the SSPX does confuse form and substance; don't leave the church even for an apparent good such as the traditional Mass; a good thing put above the church becomes an idol) but let me explain. In the '70s through the '90s, the ruling liberals in most of the American Catholic Church, besides often being heretical ("Jesus isn't God, the church is fallible, the Eucharist is just a symbolic meal," political correctness), were just as culturally idolatrous and self-righteous as we traditionalists are accused of. They told aspiring high churchmen such as me (born Episcopal, which although it is usually just as liberal as our liberals, isn't anti-high church; "high and wide," they often worship like we do) that we were bad (sinning, leaving the church) and/or mentally ill (Pope Francis' cracks about "rigidity" are more of the same; by the way, the Pope's opinions don't matter) for wanting to worship as had been done for centuries and well reflecting all our teachings. The church may be defectible and fallible in their view, but by God, they said, they were the church and we were to obey. No wonder I left the church for a long time (even doing the unthinkable, returning to an Episcopal parish: conservative, left in relative peace because of semi-congregationalism, and not rigid/self-righteous nor condescending; Anglo-Catholicism is almost the right faith, taught by the wrong side). Part of it was I was confusing form and substance, but that's exactly how Catholic liberals presented things to me in the '80s (their form "was" the church; take it or leave it). I don't mind if some Catholics want to be low-church (low and modern but not heretical: Catholic charismatics, the other American Catholics who still go to Mass); I object to the pathology I just described (which Thomas Day describes perfectly, with roots going back to before Vatican II) as well as to heresy. The church has several rites (and sub-rites such as the Novus Ordo) and many schools of spirituality and speculation, which don't always like each other even though all are Catholic. The first English Novus Ordo was borderline heretical (because of the dumb idea of "dynamic equivalence," paraphrasing, not translating); Benedict XVI "the Great" (not even that conservative, just Catholic) corrected that. Now, I have no conscience problem with the new Mass; as long as it's by the book, we're good. (The earliest, lowest Sunday Mass has been a mainstay for 45+ years for orthodox Catholics with no other official option.)
I belong to a parish 15 minutes from home that's conservative and has the Tridentine Mass as its main Sunday Mass, which I go to most of the time, and, having been Russian Orthodox (the Orthodox make the mistake too of confusing a culture with the whole church; a good traditional culture entirely Catholic), I also support the nearest Byzantine Catholic parish, which happens to be Ukrainian, going to it 12 times a year (one Sunday a month). (By the way, my first traditional Catholic Mass in person over 30 years ago was Ukrainian, one of the only places in the official church where traditional worship was still tolerated.) Been active as a Catholic again for five years and will go to a liberal parish to cover my Sunday or holy-day obligation. Grounded in small-o orthodoxy and, I dare say, far more "openness" than any Catholic liberal showed to me.
Looking to the right of the SSPX, the sedevacantist scenario can happen. (Again, given "Catholic" liberals' arrogance, presuming to speak for the church, no wonder since the '70s some traditionalists have thought apocalyptically.) It hasn't so far.
I've known enough "religious" people in my half-century on earth, and tried being one, to realize that much of the time it's just a prop, a game, or entertainment, like a hobby; left and right. Goofball clergy including Popes aren't my problem; God saw fit not to call me to be a priest so they're not my bosses, thank God. Don't get me wrong; I believe. I don't have much religion, but the religion I have is Catholic, culturally before 1965, and I don't settle for imitations.
Most Catholics use the new Mass and don't want Latin. Pope Benedict's Mass delivers the goods and comforts many, but it is not my home. The gates of hell can't prevail against Rome; I'm confident that the reform of the reform will eventually win. (Familiar to me; it's a lot like Anglo-Catholics unprotestantizing the old Book of Common Prayer.) The Tridentine Mass will keep going as a minority. Kids realize liberal Christianity isn't worth a second thought; the few religious kids want real religion.
P.S. Latin is great; long a common second language for European intellectuals, a template for sound theology and liturgy in the West, and pretty, the Romance languages' mother. "Sacred languages" are just something people naturally do. (English-speaking Protestants did it with the King James Bible.) But traditionalism isn't about Latin. Witness the Eastern rites plus Anglo-Catholics translating our services, reflected in the practices of the ordinariates.
Update: A sharp reader points out that "diocesan-approved traditional Latin Masses" simply means "traditional Latin Masses in the official church." Thanks to Benedict the Great's Summorum Pontificum, we don't need the bishop's permission.