The Declaration on Religious Freedom was at first to be a chapter on the Decree on Ecumenism and later an appendix of that same decree. It was finally given independent status as a declaration of the council.
Although it is hardly a milestone in the history of the world, (the principle of religious liberty had long since been recognised and defended by others inside and outside the church), the declaration was a major event in the history of the Catholic Church and of the Second Vatican Council.
It was by far the most controversial document produced by the council because it raised in a special way the underlying question of doctrinal development. In light of so many seemingly unequivocal condemnations of the principle of religious freedom in earlier papal documents, how could the church now turn around and endorse the principle?
The distance between Pope Pius IX’s Syllabus of Errors (1864) and Vatican II’s Declaration on Religious Freedom (1965) is more than chronological. They inhabit two different theological universes.
The document ends the so-called ‘double standard’ by which the church demands freedom for itself when in a minority position but refuses to grant freedom to other religions when they are in a minority (‘error has no right to exist’). The council declares as a matter of principle that the dignity of the human person and the freedom of the act of faith demand that everyone should be immune from coercion of every kind, private or public, in matters pertaining to the profession of a particular religious faith (n. 2).
No one can be compelled to accept the Christian faith nor can anyone be penalised in any way for not being a Christian (n. 9). The supreme model is Jesus himself and, after him, the example of the early church (n. 11).