Pope John Paul II promulgate the decree and set a date for canonisation. On 4 July 2013, Pope Francis confirmed his approval of John Paul II's canonisation, formally recognising the second miracle attributed to his intercession. He was canonised together with Pope John XXIII. The date of the canonisation was on 27 April 2014, Divine Mercy Sunday. The canonisation Mass for Blessed Popes John Paul II and John XXIII, was celebrated by Pope Francis (with Pope Emeritus Benedict XVI), on 27 April 2014 in St. Peter's Square at the Vatican (Pope John Paul had died on vigil of Divine Mercy Sunday in 2005). About
Mariology of the popes Marian themes a key part of their papacy, e.g. Leo XIII issued a record eleven encyclicals on the rosary, Pius XII invoked the first (and to date only) case of "ex cathedra" papal infallibility to establish a Marian dogma and John Paul II built his personal coat of arms around the Marian Cross. Popes have also highlighted the key Catholic Mariological theme of the link between the study of Mary and the development of a full Christology, e.g. as in Pius XII's "Mystici corporis Christi" and John Paul II's "Redemptoris Mater". Popes were highly important for the development of doctrine