Sedevacantism
- Sedevacantists believe that Paul VI (1963-1978), John Paul I (1978), John Paul II (1978-2005) and Benedict XVI (since 2005) have been neither true Catholics nor true Popes, by virtue of allegedly having espoused the heresy of Modernism, or of having otherwise denied or contradicted solemnly defined Catholic dogmas. Some of them classify John XXIII (1958-1963) also as a Modernist antipope.