It is a little known fact, at least among most ordinary Catholics and Protestants, that Vatican Council II answered the question "What is the church?" in a way that was revolutionary in many ways. De Ecclesia, the initially proposed response to this question, identified Christ with the Roman Catholic Church. Membership was thus based on acknowledging the authority of the Roman pontiff; the maximal extension of the infallible magisterium; and ecumenical minimalism. The drafters were clearly concerned to protect the old thinking, and saw the church as "deeply concerned about the question of authority." Regardless of what some modern Catholic apologetics groups now say, this draft was easily rejected. The reason? The historical context was not big enough. It was not big enough for a largely Western church that was now faced with the entire global situation.
Thus Sacrosanctum concilium (December 4, 1963) says in the very first sentence that it wants "to adapt more closely to the needs of our age those institutions which are subject to change; to foster whatever can promote union among all who believe in Christ" (No. 1). Regarding the liturgy, it is added in No. 2: The liturgy is meant to "show forth the Church, a sign lifted up among the nations, to those who are outside, a sign under which the scattered children of God may be gathered together until there is one fold and one shepherd." The point is that the liturgy was to have, as a major emphasis, a reconciling function. This unity was understood to be a matter for reconciliation but not cultural uniformity.
The result has been a forty-plus year growth into real ecumenism by the Roman Catholic Church. This even began at the Council itself when Pope John XXIII welcomed Protestant observers to the Council (see photo at left).
Serious Catholic leaders and scholars are deeply involved in ecumenism in 2008, and much gain has been made over the past few decades. Among these gains are many that have developed informally with evangelicals, in a growing field of dialog and unity. People on the left have used all of this to support causes and beliefs clearly rejected by Vatican II, while some on the right have insisted that the Council did not mean some of what it actually said. (Listening to popular radio-based Catholic apologetics I sometimes wonder if they understand Vatican II.) For me this great decision opened the door to the kind of practical, unofficial, ecumenism that I have found extremely useful in working with my Catholic brothers and sisters in so many kingdom oriented ways.