Istituto Mater Boni Consilii

The Institute of the Mother of Good Counsel (Istituto Mater Boni Consilii; Institutum Mater Boni Consilii; IMBC) is a sedeprivationist traditionalist Catholic religious congregation based in Italy.

Adhering to the Thesis of Cassiciacum of the French theologian Bishop Michel-Louis Guérard des Lauriers, the institute teaches that while Pope Francis is a duly elected pope, unless he recants the doctrinal changes brought by the Second Vatican Council, he lacks the authority to either teach or govern, and is only pope materialiter sed non formaliter, that is "materially but not formally".

History
The Institute of the Mother of Good Counsel was formed in December 1985, when four Italian priests left the Society of Saint Pius X (SSPX). These priests were Father Francesco Ricossa, Father Franco Munari, Father Curzio Nitoglia, and Father Giuseppe Murro. These priests were dissatisfied with the position the SSPX, which acknowledged John Paul II as a true pope but disobeyed him.

The IMBC was first based in Nichelino, Province of Turin, Italy, then later in Verrua Savoia, Province of Turin (currently the Metropolitan City of Turin), Italy.

In September 1986, two priests of the institute traveled to Raveau, France, for the IMBC, to meet the French sedeprivationist Bishop Michel-Louis Guérard des Lauriers, whose Thesis of Cassiciacum the IMBC adopted.

In May 1987, the founders of institute wrote a retraction of doctrines they professed in the past when they still belonged to the SSPX.

Bishops
In 1987, Des Lauriers consecrated to the episcopacy Father Giorgio Munari, an Italian priest and member of the IMBC. However, on 26 October 1990, Munari resigned from the episcopacy and priesthood.

From 1990 to 2002, the IMBC was assisted by Bishop Robert McKenna, an American sedeprivationist bishop, who had also been consecrated by Des Lauriers in 1987.

On 16 January 2002, McKenna consecrated to the episcopacy Father Geert Stuyver, a Belgian priest and member of the IMBC, who administers to the needs of the institute at present.

Present day
The IMBC is currently present in Italy, France, Argentina, Hungary, the Netherlands and Belgium. It celebrates the Tridentine Mass following the missal of Pope Pius V, as amended by Pope Pius X, rejecting the following amendments by Pope Pius XII and Pope John XXIII, without mentioning the Pope's name in it (non una cum). It owns a seminary, named Seminary of Saint Peter the Martyr, and published a magazine called Sodalitium.

The Institute is also connected to three study centers (the Giuseppe Federici Study Center, the Paolo de Töth Study Center and the Davide Albertario Study Center ), whose purpose is the study and defense of Catholic doctrine; to these is added the San Simonino Committee, which aims to restore the public cult of Simon of Trent, suppressed in 1965 by Archbishop Alessandro Maria Gottardi.

The IMBC also uses the name Sodalitium Pianum as an alternative name; this was the name of an unofficial group of theologians and others set up in the early twentieth century by priest and church historian Umberto Benigni to report to him those thought to be teaching Modernist doctrines.