Godless Human Reason and the One True Church

Pope Pius IX's encyclical Quanta Cura condemns "naturalism" or the "liberty of perdition," specifically paragraph 2 of section 3 which includes a condemnation of this:

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.

He continues by asserting it is not just religious freedom that is the problem but also the worship of human reason, which is something very prevalent at universities:

But, while they rashly affirm this, they do not think and consider that they are preaching "liberty of perdition;" and that "if human arguments are always allowed free room for discussion, there will never be wanting men who will dare to resist truth, and to trust in the flowing speech of human wisdom; whereas we know, from the very teaching of our Lord Jesus Christ, how carefully Christian faith and wisdom should avoid this most injurious babbling."

His Syllabus of Errors, which accompanies the encyclical, condemns indifferentist and latitudinarian propositions which deny the absolute truthfulness of only the Catholic Church:

III. INDIFFERENTISM, LATITUDINARIANISM

15. Every man is free to embrace and profess that religion which, guided by the light of reason, he shall consider true. —Allocution "Maxima quidem," June 9, 1862; Damnatio "Multiplices inter," June 10, 1851.
16. Man may, in the observance of any religion whatever, find the way of eternal salvation, and arrive at eternal salvation. —Encyclical "Qui pluribus," Nov. 9, 1846.
17. Good hope at least is to be entertained of the eternal salvation of all those who are not at all in the true Church of Christ. —Encyclical "Quanto conficiamur," Aug. 10, 1863, etc.
18. Protestantism is nothing more than another form of the same true Christian religion, in which form it is given to please God equally as in the Catholic Church. —Encyclical "Noscitis," Dec. 8, 1849.

However, Pope Pius IX's encyclical and Syllabus seem to contradict the Vatican II document Dignitatis Humanæ, which is subtitled in seeming direct contradiction to condemnations of "religious freedom" (i.e., "Declaration on Religious Freedom — On the Right of the Person and of Communities to Social and Civil Freedom in Matters Religious Promulgated by His Holiness Pope Paul VI on December 7, 1965"). Although one cannot deny the Vatican II council's authority, it seems that Dignitatis Humanæ advocates separation of Church and state, relativism, humanism (i.e., a trust in human reason without the Church and the Catholic faith as its guide), the inutility of the Church in salvation, and the subjection of the Church to state, among other things. Yet it does not. Its audience is the world, including non-Catholics; and its message is that the Church does not and will not force converts. Nevertheless, the Catholic faith is still the only true one (Dominus Iesus).