On May 21, 2000, Pope John Paul II canonized a group of 25 saints and martyrs who had died in the Mexican Cristero War. The vast majority are Catholic priests who were executed for carrying out their ministry despite the suppression under the anti-clerical laws of Plutarco Elías Calles after the revolution in the 1920s.

Priests who took up arms, however, were excluded from the process. The group of saints share the feast day of May 21.

On 15 November 2005, Pope Benedict XVI issued an Apostolic Letter declaring the following individuals "blessed" and establishing their memorial feast on 20 November. November 20 is the official anniversary in the Mexican civil calendar of the start of the Mexican Revolution, with the promulgation of the Plan of San Luis Potosí in 1910 by Francisco Madero.

The Cristero War or Cristero Rebellion (1926–29), also known as La Cristiada, was a widespread struggle in many central-western Mexican states against the secularist, anti-Catholic and anti-clerical policies of the Mexican government. The rebellion was set off by enactment under President Plutarco Elías Calles of a statute to enforce the anti-clerical articles of the Mexican Constitution of 1917 (also known as the Calles Law). Calles sought to eliminate the power of the Catholic Church and organizations affiliated with it as an institution, and also suppress popular religious celebration in local communities.

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