High Quality Content by WIKIPEDIA articles! Holy See–Soviet Union relations were marked by a long-standing persecution of the Roman Catholic Church by the Soviet Union. After a long period of resistance to atheistic propaganda beginning with Benedict XV and reaching a peak under Pius XII, the Holy See attempted to enter in a pragmatic dialogue with Soviet leaders during the papacies of John XXIII and Paul VI. In the 1990s, Pope John Paul II`s diplomatic policies were cited as one of the principal factors that led to the dissolution of the Soviet Union.