Right now I want to deal with the issue of religious liberty. "Separation of Church and State" is a different, yet related issue for later in the thread (for now, let it be said that there is a true separation--two spheres, temporal and spiritual, governed by two powers, state and church--always and still affirmed and a false separation--the state acts without any reference to objective truth--always and still rejected).
A "hierarchy of truth" approach is the best to understanding religious liberty. This does not mean that some truths are more important than others, but rather understanding certain truths requires understanding others first.
The first such truth is the dignity of the human person as a creature of God who's end is also God. All men share this common end. (Pius XII, Summi Pontificatus, 38). Therefore, by their very dignity all men have the right to pursue that end. Rights exist so duties can be fulfilled. Since men have the duty to God to pursue this end, the state can never impede this pursuit.
The next truth we must understand is that faith must be free. Man cannot be coerced into coming to God. (Pius XII, Mystici Corporis, 104; Leo XIII, Imortale Dei, 36; Bl. Gregory X, Protection of the Jews, 3). The state can therefore never coerce man to the truth and to God against his will. It bears pointing out here, that when the Church sanctioned force by the state against non-Catholics, it was never on the grounds of forcing conversions, but rather to protect the just ordering of society, whether or not they were right in seeing such individuals as threats to that order. (cf. St. Robert Bellarmine, Treatise on the Civil Government, ch. 21)
These are the bases for the Church's doctrine of religious liberty. However, there is also an erroneous version of this doctrine which was popular in the 1800s and a result of the excesses of Liberalism. I would like to now work my through some relevant documents from that period through Dignitatis Humanae from the Second Vatican Council.
The first text is the passage cited in the CCC 2109 (see post #4 above) from Quanta Cura by Bl. Pius IX (which I will divide in two):
For you well know, venerable brethren, that at this time men are found not a few who, applying to civil society the impious and absurd principle of "naturalism," as they call it, dare to teach that "the best constitution of public society and (also) civil progress altogether require that human society be conducted and governed without regard being had to religion any more than if it did not exist; or, at least, without any distinction being made between the true religion and false ones." And, against the doctrine of Scripture, of the Church, and of the Holy Fathers, they do not hesitate to assert that "that is the best condition of civil society, in which no duty is recognized, as attached to the civil power, of restraining by enacted penalties, offenders against the Catholic religion, except so far as public peace may require."
First, we must avoid "naturalism:" that is, the idea that civil society should be absolutely free from any acknowledgment of God or without any distinction between truth and error in regards to God. Likewise, the state must protect the rights of the Church.
From which totally false idea of social government they do not fear to foster that erroneous opinion, most fatal in its effects on the Catholic Church and the salvation of souls, called by Our Predecessor, Gregory XVI, an "insanity,"2 viz., that "liberty of conscience and worship is each man's personal right, which ought to be legally proclaimed and asserted in every rightly constituted society; and that a right resides in the citizens to an absolute liberty, which should be restrained by no authority whether ecclesiastical or civil, whereby they may be able openly and publicly to manifest and declare any of their ideas whatever, either by word of mouth, by the press, or in any other way."
Here we must also bring forth the citation to Mirari Vos by Gregory XVI. He is concerned with the rationalists who deny the necessity of faith for salvation:
Now We consider another abundant source of the evils with which the Church is afflicted at present: indifferentism. This perverse opinion is spread on all sides by the fraud of the wicked who claim that it is possible to obtain the eternal salvation of the soul by the profession of any kind of religion, as long as morality is maintained.
Here we see he is not concerned with the Catholic notion of the liberty of conscience (more on this later), but rather the notion of it based on religious indifferentism:
This shameful font of indifferentism gives rise to that absurd and erroneous proposition which claims that liberty of conscience must be maintained for everyone.
So, the second error we must avoid is that freedom of conscience based on religious indifferentism, by which man's conscience cannot be bound in any way, by God, by the Church, or by the state. The third, and related error to be avoided, is an absolute freedom, whereas the state can never limit in any way false religious activity, false speech, or false publishing.
These same errors are also summarized in Immortale Dei by Leo XIII, paragraphs 25 and 26.
Now we will begin to see how these principles are synthesized and put into practice.
Next, Leo XIII in Libertas draws the distinction between true and false liberty of conscience:
30. Another liberty is widely advocated, namely, liberty of conscience. If by this is meant that everyone may, as he chooses, worship God or not, it is sufficiently refuted by the arguments already adduced. But it may also be taken to mean that every man in the State may follow the will of God and, from a consciousness of duty and free from every obstacle, obey His commands.
He then adds a note about how the state can act in a practical situation:
For this reason, while not conceding any right to anything save what is true and honest, she does not forbid public authority to tolerate what is at variance with truth and justice, for the sake of avoiding some greater evil, or of obtaining or preserving some greater good. God Himself in His providence, though infinitely good and powerful, permits evil to exist in the world, partly that greater good may not be impeded, and partly that greater evil may not ensue.
Here he rules out the right to err (see also CCC 2108), but at the same time affirms that it is permissible to tolerate errors to prevent a greater good from being impeded.
Pius XI also, in passing, differentiates between true and false freedom of conscience in Non Abbiamo Bisogno:
We lately declared Ourselves happy and proud to wage the good fight for the liberty of consciences. No indeed (as someone, perhaps inadvertently, has represented Us as saying) for "the liberty of conscience, which is an equivocal expression too often distorted to mean the absolute independence of conscience and therefore an absurdity in reference to a soul created and redeemed by God.
Next, Pius XII, in Ci Riesce takes up where Leo XIII left off in describing practical situations:
Reality shows that error and sin are in the world in great measure. God reprobates them, but He permits them to exist. Hence the affirmation: religious and moral error must always be impeded, when it is possible, because toleration of them is in itself immoral, is not valid <absolutely and unconditionally.>
Moreover, God has not given even to human authority such an absolute and universal command in matters of faith and morality. Such a command is unknown to the common convictions of mankind, to Christian conscience, to the sources of Revelation and to the practice of the Church. To omit here other Scriptural texts which are adduced in support of this argument, Christ in the parable of the cockle gives the following advice: let the cockle grow in the field of the world together with the good seed in view of the harvest (cf. <Matt.> 13:24-30). The duty of repressing moral and religious error cannot therefore be an ultimate norm of action. It must be subordinate to <higher and more general> norms, which <in some circumstances> permit, and even perhaps seem to indicate as the better policy, toleration of error in order to promote a <greater good.>
Again, here we see again that suppressing error, while permissible, is subject to other norms, such as the promotion of a greater good. This is the bedrock for the practical decisions in Dignitatis Humanae.
continued....