As a young man Sáenz Arriaga was brought up in the spirit of the Cristero movement, Miguel Pro and other Catholics who fought against the government of Mexico in the 1920s.

Sáenz y Arriaga placed great emphasis on the Catholic doctrine of the "Kingship of Christ".
When the Vatican II reforms began to be implemented in Mexico and North America, it was Fr.
Sáenz y Arriaga who led the fight against them.

His uncompromising traditionalism led to a rejection of the new Conciliar Church, and he became the first to propound the doctrine of sedevacantism, which maintains that, since the death of Pope Pius XII, there has been a sede vacante in Rome because the following so-called popes espoused the heretical teachings of the sham Second Vatican Council.

Fr.
Sáenz y Arriaga later incorporated these ideas in his books La nueva iglesia montiniana (The new Montinian Church) (1971), and Sede Vacante: Paulo VI no es Papa legítimo (Sede Vacante: Paul VI is no longer a legitimate Pope) (1973).
In these books he stated that Paul VI had forfeited his papal authority through public, pertinacious and manifest heresy, a position which he had reportedly held for some time.
 He was a catalyzing influence on lay and clerical Catholic traditionalists who opposed Vatican II in Mexico and North America, persuading them to defend and maintain the "True Faith", setting up independent chapels and churches and soliciting and procuring consecrations to create alternative lineages of bishops.
As a young man Sáenz Arriaga was brought up in the spirit of the Cristero movement, Miguel Pro and other Catholics who fought against the government of Mexico in the 1920s.
Sáenz y Arriaga placed great emphasis on the Catholic doctrine of the "Kingship of Christ". When the Vatican II reforms began to be implemented in Mexico and North America, it was Fr. Sáenz y Arriaga who led the fight against them.
His uncompromising traditionalism led to a rejection of the new Conciliar Church, and he became the first to propound the doctrine of sedevacantism, which maintains that, since the death of Pope Pius XII, there has been a sede vacante in Rome because the following so-called popes espoused the heretical teachings of the sham Second Vatican Council.
Fr. Sáenz y Arriaga later incorporated these ideas in his books La nueva iglesia montiniana (The new Montinian Church) (1971), and Sede Vacante: Paulo VI no es Papa legítimo (Sede Vacante: Paul VI is no longer a legitimate Pope) (1973). In these books he stated that Paul VI had forfeited his papal authority through public, pertinacious and manifest heresy, a position which he had reportedly held for some time.  He was a catalyzing influence on lay and clerical Catholic traditionalists who opposed Vatican II in Mexico and North America, persuading them to defend and maintain the "True Faith", setting up independent chapels and churches and soliciting and procuring consecrations to create alternative lineages of bishops.
Joaquín Sáenz y Arriaga