Letter is not signed, the priest may be a Novus Ordo or other questionable ordained "priest", in which case, it is undoubtable better to go with a valid SSPX priest. The SSPX is a priestly fraternity, like a cooperative, each priest has his own opinion on the matter of joining with Rome, and many other issues like EENS/BOD, Covid shots, dress code........ Or even worse the priest writing the letter could even be a sodomite, a child molester or interested in women parishioners.

For what it’s worth, I was there at the sermon. I know the priest. He is not a homo, child molester or a novus ordo preist.
There are a number of other cathinfo members that will say the same as me.

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No.  He is a traditional priest, validly ordained by B. Williamson or B. Faure.
He refused to close for 2 weeks to flatten the curve, when SSPX chapel was closed.

Now we know, but as to the rest, we do not know. He has absolutely no reason not to sign the letter.

The fact that it is not signed gives me pause.

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I did not get permission from the priest to publish it.
So I did not include the priest's name.
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However, it is an excellent sermon and sorely needed,
as the SSPX is being destroyed by the headquarters.
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Actually, most of the sermon is from Pope Pius VI.
If that is not good enough for you, then too bad.
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Who’s the priest?

Puzzle has a major axe to grind with all (legit, non-Indult) Traditional groups.

He is a parishioner at Fr. Perez's chapel in California, and is reeling from the setbacks there at the moment.

So he posted dozens of times about sɛҳuąƖ abuse allegations over the past 4 decades at any Trad group he could find. Re-hashing things that are many years -- as many as 40 years -- past. I had to lock a few of his threads, where he was muck-raking and obsessing.

If you have enough years (50?) and a large enough pool (how many priests in Tradition over the past 50 years? How many Traditional Catholic FAITHFUL?) you can collect and make a PILE of just about anything. That doesn't necessarily mean there's a conspiracy, cover-up, or pattern.

I'll give you your pattern right here: ORIGINAL SIN. You're not going to find sinlessness in ANY group of human beings, not even divine institutions like the Catholic Church. So you can give up on that little quest RIGHT now. If that means you apostatize, then may God have mercy on your soul. 

I don't know why Puzzle feels the need to tear down every other group -- is it because he suspects or SEES problems at his own chapel? If everywhere else is worse, then even the problems he sees at home seem justifiable to continue attendance. Maybe that's how he sees it.

At any rate, his presence here is incurably toxic, so I'm banning him. Last week when I locked those muck-raking threads, I almost banned him. But I wanted to give him a chance. Apparently he's incorrigible.

His toxicity was proven in this thread, wherein he reads the words of a very serious, obviously well educated, somewhat cerebral priest, and with ZERO basis jumps to the rash judgment that he is mired in the basest sins of the flesh. 

Puzzle's soul is NOT in a good state. Such wretched, bitter, unhappy, malicious souls do CathInfo NO credit.

In MHO the comparison is not fair. During the French revolution, similar to the English reformation, it was evident to everyone who was right and who was wrong, black and white situation, even if you didn't know your catechism.