Pope John XXIII called the council to assist the Church in adapting to changes that were more rapidly taking place in the world - political, social, technological, etc.

Most Catholics believe that Vatican II was led by the Holy Spirit, although they may disagree on how good or bad post-conciliar changes were.

It was for many reasons. The largest was because the Catholic Church needed to press a lot of reform in order to continue to be relevant in modern society.

For example, prior to the Council, all Masses had to be be said in Latin. This made it difficult for people to really understand the mass and as such it was turning people away from the Church. The SVC met to discuss Canon Law and decided that Mass did not have to be said in Latin as there was no evidence of God directing that it must be that way.

There had been many other councils held prior to the SVC, and most of them were for the same reason -- a real need for reform.

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