In his book Theological Highlights of Vatican II (Paulist Press 1966) Joseph Ratzinger indicates six concrete problems faced by the Council.
1. The problem of divine worship.
2. The problem of centralism in the Church.
3. The problem of relations with non-Catholic Christendom and the ecumenical movement.
4. The problem of new directions in the relations between Church and State, or what might somewhat imprecisely be labeled the end of the Middle Ages, or even the end of the Constantinian era.
5. The problem of faith and science, or, more specifically, the problem of faith and history, which had become a basic problem for faith through the triumph of the method of historical criticism.
6. The problem of the relation of Christianity to the modern ethic of work, to technology, and in general to the new moral problems posed by a technological society.
The Council Fathers, in their attempt to bring the Gospel afresh to the modern world, charted out the course for the way to begin to resolve these difficulties so that all men might come to the knowledge and the love and mercy of Jesus Christ. As Cardinal and as Pope, Ratzinger has been exemplary in furthering that course of bringing the Gospel, in it's integrity, to all men of good will, of making Christ more and more accessible to the modern mind and circumstance.
