I appreciate this thoughtful post, but I think it oversimplifies things.
The SSPX are VERY small. The largest estimates have them at around 1.5 million members world wide. The Catholic Church as a whole (the SSPX are within it of course, and are not schismatic) numbers in the billions.
In the larger group of course only a percentage live authentic Catholic family lives. The percentage that reject contraception for instance is scandalously small.
That said, the Church has never been a “pure” Church, and never will be. As Oscar Wilde said (on one of those occasions where he put his wit to GOOD use) “The Catholic Church is for saints and sinners… respectable people have the Anglicans”
All true
“Even if Catholics faithful to Tradition are reduced to a handful, they are the ones who are the true Church of Jesus Christ.” - St. Athanasius, AD 373
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“It is granted to few to recognize the true Church amid the darkness of so many schisms and heresies, and to fewer still so to love the truth which they have seen as to fly to its embrace.” -St. Robert Bellarmine
Why are the numbers of Catholics who believe what the Church professes so small? I do not know. I do know that it is incredibly hard being on the front lines trying to convince those around us in the NO Church that contraception is evil. It is hard being in the front lines trying to convince everyone around us that abortion is fundamentally evil. It is hard being in the front lines standing up for a traditional liturgical praxis that clearly recognizes our Eucharistic Lord.
All of that said, it seems the SSPX misdirects their fire.
They only practice Catholicism as it was from 1563 until 1963

The target is the same. Satan.
Suppose you are right; you are the one true Church and even John Paul II and Benedict XVI got it wrong on things like freedom of religion etc. Suppose you manage (despite the fact that the Pope has called on you to recognize the Council and stop claiming a Magesterium superior to his) to remake the Church in the SSPX’s image.
NO NO NO ! First, I’m not SSPX clergy, nor do I attend their Masses. I’m a member of a diocesan parish.
The parallel Magisterium issue is moot at this point. That issue is history, barring a turning away from our Holy Father’s hand he has offered. I too, had concerns about that, and along with Bishop Fellay calling BXVI a “perfect liberal”. I was about to formally join the local Chapel after a few weeks of assisting the Mass there, but I haven’t been back since the comment. It’s not an issue for me anymore, because obviously, it isn’t one for the Pope.
And the SSPX image ? They have no image, nor have they ever formed one. Stigma, yes. Unjust as history will prove imo. The Church doesn’t need to be remade. She needs to be reaffirmed as at Trent. Trent is the measuring stick, not the Society. To say such would be pride.
You know how hard it is to proclaim the truths that even the Vatican II Church proclaims? Just wait. You would be almost entirely by yourselves arguing against freedom of religion in a country like the United States, which prides itself on its pluralism and its freedoms.

, are you agreeing that the pastoral efforts of VII have failed in the US ?
I for one am not sure Christ would be on your side in such a crusade, for I believe that Vatican II is a valid council, and the teachings of the Popes post the Council on things like freedom of religion come from Christ.
I really think, despite the tone of your post, which is Christian and humble and admirable, that the argument you making smacks of a bit of pride here. (I am NOT saying you are prideful!!! Not at all… just the argument).
I do not think throwing away Vatican II is the answer to the Church’s problems. I do not think that embracing a Catholicism that denies everything about the enlightenment (even those things about the enligtenment that were good) is a very smart way to go. I do not think it is what Christ wants. (I look to the Popes and the Magesterium to guide me on that… yes… the CURRENT ONES.)
Winning souls for Christ has been the Church’s mission from day 1. Christ instructed the Apostles to do this.
To engage in dialogue instead of war, is of benifit. And the doors of the Church must remain open for all who wish to enter. Continued dialogue, in the interest of peace, and in hopes of conversions, is fine.
But the Church can only enrich other religions, by making it known to them what we believe. These other religions have nothing to offer the Church other than their respect of Her.
Do they ? A Baptist may question the practice of kneeling before a statue of Our Lady. Fair enough. We can explain if they will listen. But on the more extreme end, those of a religion that rejects Jesus Christ dares to tell HMC to omit a prayer in the Her Liturgy, which by doing so, is a forsaking of Her mission and the uncrowning of Christ the King !
And why did this issue arise ? Because of the Summorum Pontificum. The prayer wasn’t an issue until the Mass was freed of stigma once and for all. Then comes the lifting of the excommunications. Again, it was known that Bishop Williamson 's thoughts were an issue. But it was only brought up after the official announcement on the excommunications.
See what all of this ecumenical effort has gotten us ?
Attacks on our Holy Father. A world leader being told he should step down by those who wish they were. Bishops publicly questioning the Bishop of Rome.
So now what ? The VII teaching on Religious Freedom is the measuring stick against which HMC’s Doctrine and Dogmas will be judged ? Shouldn’t it be the other way around ?
That would be more in line with Tradtition wouldn’t it ?