Arnaldo Vidigal Xavier da Silveir belonged, both on the paternal side and on the maternal side, to families known in Brazil for their prominence, especially in politics, in law and entrepreneurship. He was born in 1929 in Sao Paulo, Brazil where he studied with the Jesuit fathers, first in St. Louis College, then in Central Seminar of the Immaculate Conception.

He later entered the Faculty of Law of Catholic University of São Paulo, dove, In the 1956, he graduated in Legal and Social Sciences. He practiced as a lawyer until his last days, also managing the legal department of the well-known construction company Adolpho Lindenberg. He was a professor of Propedeutics of History and then say Morality and Sociology in the Faculty of Philosophy, Sciences and Letters Saint Benedict, and in the Faculty of Economic Sciences Heart of Jesus, both from the Pontifical Catholic University of Sao Paulo.
He was one of the founders of the culture monthly Catholicism, published under the aegis of Msgr. Antonio de Castro Mayer, bishop of Campos, and author of important studies on the Magisterium of the Church, the Conciliar Magisterium and pontifical infallibility. Among his numerous writings, aimed primarily at the defense of the Catholic Faith and Orthodoxy, without any concern on his part about career or academic prestige, we remember:

• What is the doctrinal authority of pontifical and conciliar documents(nº 202, out. 1967);
• NNot only heresy can be condemned by ecclesiastical authority(nº 203, nov. 1967);
• Atos, gestures, attitudes and omissions can characterize the heretic(nº 204, dic. 1967);
• In response to an imaginary progressive reader (nº 206, feb. 1968);
• Can a Catholic reject the Human Life? (nº 212/214, ago-there. 1968);
• There may be an error in the teaching document? (nº 223, July 1969);
• Public resistance to decisions by ecclesiastical authority (nº 224, ago. 1969).

These studies have had great repercussions and have been reproduced by the Catholic press throughout the world. Some of them have been translated into English and published under the title Can Documents of the Magisterium of the Church Contain Errors? (The American Society for the Defense of Tradition, Family and Property – TFP, Spring Grove, Pennsylvania 2015),
In the 1970 Arnaldo Xavier da Silveira posted, limited edition, the Considerations on the “Ordo Missae” of Paul VI which included a study on Theological hypothesis of a heretical Pope. The work was later published in French, with the title The New Mass of Paul VI: What to think? (Diffusion of French Thought, Chiré-en-Montreuil 1975), but the diffusion of the work, according to what the author thought, it was prohibited by Paul VI himself. The part dedicated to the “heretic Pope” translated in 2016 the care of One Voice Among Many, was published in Italian, with the title Theological hypothesis of a heretical Pope from Edizioni Solfanelli of Chieti (hypothesis that we consider absurd and to which, while appreciating the seriousness of the author, we have never joined nor will we join, n.d.r.), and in 2018 in English, with a new chapter and update with the title, Can a Pope be … a heretic? (Roman Paths, Portugal 2018). In the 2017 Arnaldo Vidigal Xavier da Silveira was one of the first signatories of the Filial correction to Pope Francis. In the conference on modernism organized in June of 2018 by the Lepanto Foundation, his name has often been remembered as one of the most serious contemporary scholars of the crisis of the Church.
Arnaldo Vidigal Xavier da Silveira was a founding member and one of the directors of Brazilian Society for the Defense of Tradition, Family and Property, the first of the associations with this name (TFP) which exist today in numerous countries on the five continents, all inspired by the work and thought of Pliny Correa de Oliveira. Comforted by the sacraments of the Church, died in Sao Paulo on 19 September of this year, following cardiac complications. He leaves a widow and four children and grandchildren.
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The occasion allows us to say that the Christus Rex Circle believes both the internal and external doctrine of the TFP to be profoundly erroneous, at least since Mons. de Castro Mayer took a justified public distance from it. Above all, we do not share Sdeplenism, fallibilism, anticlerical tendencies, sectarian modes, the reactionary mentality, passéism, the oddities, the ambiguities and personal doctrines of the founder, handed down and still taken into consideration. We recognize its indisputable merits both on the level of defense of the Faith of all time and above all on the political level in post-conciliar Brazil and in the 1970s..