Since the 1960s, a confrontation has been unfolding within the Catholic Church between modernists, who support the updated Mass, and traditionalists, who adhere to the old Tridentine Mass. With the ascension of the new pontiff Leo XIV to the papal throne, these disputes have only intensified.

In the second half of the 20th century, the Catholic Church faced a serious crisis related to the confrontation between modernists and traditionalists. The most radical minority of the latter broke away from the Holy See, creating autonomous communities of sedevacantists—Catholics who do not recognize the current Popes and consider the papal throne temporarily vacant.