Well, even most sedes had no problem with "Una cuм" Masses before Fr. Cekada came along and invented this NOVEL and self-serving doctrine.

The idea that assisting at a regular Tridentine Mass, wherein the priest prays for the Pope "one with Pope N... and our Bishop N..." somehow means we are one with his heresies and/or personal sins -- that's an insane idea that never once entered into any Traditional Catholic's mind before Fr. Cekada came along.

Fr. Cekada lived and had his apostolate in CINCINNATI, OH which is a haven of Traditional Catholicism, with around TWELVE Traditional Catholic flavors/groups/options.

So you see, it's understandable (humanly speaking) that Fr. Cekada would have naturally been tempted to come up with a scheme to "eliminate the competition" and make his flock permanently his own.

And so he did.

And for that very human, selfish, sinful, and base move, I lost all respect for him.

I've been a Traditional Catholic my whole life, and I'm in my 40's, having grown up at an independent chapel. I know Traditional Catholicism intimately. I know how they thought and believed in the early days. They avoided N.O. Masses, but they attended pretty much ANY Tridentine Mass, as long as the priest was valid. None of this "anti-Una cuм" nonsense. And sedevacantism was a side thing, a personal opinion, not something you included in your identity. ("I want to find a good, Traditional, Sedevacantist girl and get married...") Those words in quotes would have sounded like this: "I want to find a good, modest, Traditional Catholic girl named Emily and get married, and then..." Or mentioning specific interests/hobbies that your future spouse would have. It would be unrealistic and cute, something kids would say about "when they grow up" -- but no adults would say it or mean it.

"This famous Una cuм of the sedevacantists...ridiculous! ridiculous .... it’s ridiculous, it's ridiculous. In fact it is not at all the meaning of the prayer"- Archbishop Marcel Lefebvre, retreat at St-Michel en Brenne, April 1st, 1989

I'd show you where this ERROR, this distorted idea of the Una cuм prayer came from -- but you wouldn't like it, any more than Lucia, Francisco, and Jacinta did when Our Lady showed it to them. 

Well, even most sedes had no problem with "Una cuм" Masses before Fr. Cekada came along and invented this NOVEL and self-serving doctrine.

Father Cekada did some good work, but he did come up with a few doozies over the years as well, in addition to the "una cuм" (which even the Dimond Brothers reject)

1) "Cekadism" (notion that theologians enjoy some kind of role in the Ecclesia Docens nearly to the point of infallibility) -- rejected explicitly by Monsignor Fenton

2) Terri Schiavo analysis (scandalous and wrong)

3) Reasons for removing the Prayers after Low Mass

Fr. Cekada was the one apparently who came up with this una cuм nonsense, but doesn't Bp. Sanborn went along with him?

I had the impression that Bp. Sanborn swears by the una cuм rule too, saying that it is sinful to attend at masses that include the Pope's name in the Canon.

I didn't know the Dimonds rejected non una cuм. That's interesting. I'd love to know their rationale.

go to vatican catholic .com and search "una cuм mass" and some articles pop up where they explain their position.

From Bishop Sanborn:
"Finally I hold that the traditional Latin Mass which is offered together with (una cuм) the Novus Ordo hierarchy is objectively sacrilegious. Consequently I affirm that active participation in Masses or services in which the name of a Novus Ordo hierarch is mentioned is objectively a mortal sin."
https://romancatholicinstitute.org/hello-world/

There we have it. Thank you.

Being a Traditionalist Catholic is so interesting because every now and then we get new dogmas proclaimed. And you get to choose which ones you accept. 

A digression, but I can't stand the phrase "I assist at Mass."

Sounds like "active participation."

Or, "I help the priest at Mass.  I'm his assistant.  I'll assist him"

I prefer "I go to Mass."

assist

ə-sĭst′
intransitive verb

• To give help or support to, especially as a subordinate or supplement; aid.
• To give aid or support.
• To be present, as at a conference.

Only the third definition fits Mass attendance.