The Second Vatican Ecumenical Council was in effect from October 1962 to December 1965. The council introduced significant changes with regard to mass, dogma, and ecumenical practices.
The Council granted permission to celebrate mass in the people's common language. Prior to this ruling, mass was recited in Latin, and priests delivered the liturgy with their backs facing parishioners.
In addition, the Second Council created a culture of unprecedented ecumenical tolerance. The Council resolved, for example, that "Jews should not be presented as rejected or accursed by God" and that "the Church... decries hatred, persecutions, [and] displays of anti-Semitism."
The Council's resolutions on birth control, evolution, cosmology and other controversial issues were of interest to Catholics and non-Catholics alike. In the secular world, the Second Council quickly gained a reputation as socially and theologically liberal.
In his opening address to the Council, Pope John XXIII called for an era of "a new enthusiasm, a new joy, and serenity" for lay members. It was his hope that such enthusiasm, joy, and serenity be the Council's legacy.