La Pira saw the history of the world in all its constituents (religious, political, social, cultural) in terms of the recognition of the Resurrection of Christ. “If it be true, as true it is, that Christ is risen; if the Revelation (both Old and New Testaments) be true, as true it is; if the Pentecost (the institution of the Church) be true, as true it is, then the entire history of the world has a meaning, a direction and a well-defined goal.” What it boils down to is that for La Pira, as for Fornari, the history of the world is the biography of one person: Christ.

The Church is the sacrament of unity, the authoritative interpreter of the “signs of the times” which increasingly show the tendency towards unity, and is a function of the reality of the mystical body of Christ. The redemptive power of Christ works in fact and in deed through the Church and acts to the benefit of all men who in act or in potential are associated with Christ.
It is in this context that we must view his particular and individual concept of the importance of the unity of the Churches also as a necessary premise of the unity of peoples and nations. “No longer, therefore, East and West divided by a chasm of distrust, but fraternally linked together by a bridge of hope.”
And it is in this perspective that he sees the “revolutionary” momentousness of the Second Ecumenical Council of the Vatican.

From here you may access:
§  The Second Ecumenical Vatican Council (Vatican II)
§  La Pira and the Council