Modernism in Vatican II: Declaration on the Relation of the Church to non-christian religions - Nostra Aetate
A response

It would be theologically incorrect to assert that there is no truth outside the Church. Although their understanding of God is full of errors, it is nevertheless the "same God". The monotheistic religions have an entry point to discuss Jesus the Saviour. This criticism of Islam is clear in the address. This clarifies any ambiguity.

Pope Benedict XVI's Regensberg Address after which a nun was martyred by Muslim violence remains on the Vatican website. There is a prudent diplomatic footnote showing "respect" for Islam as a major world religion. It is always a good idea to respect one's opponent.

Pius X was concerned with the "falsities" in other religions in PASCENDI DOMINICI GREGIS (14), not inter-religious dialog where commonality is an entry point to presenting the Gospel, as St. Paul did when he spoke to the Greeks of the statue to the "Unknown God" among all their false gods. (Acts 17:23)

Towards the Jews, it seems to believe that Christ has already reconciled Christians and Jews, simply ignoring the fact that Judaism has not converted and remains hostile to Christ, maintaining its false temporal messianic hope. This supposed conciliation renders uncertain the theology of the substitution, which involves, as we know, the radical and obvious substitution of Christianity for Judaism, as the only true revealed religion (NA 4).

We have an article on Jewish/Catholic relations. The comments to the left are indicative of the "double blindedness" between Catholics and the Jewish world. Replacement theology is plain bad theology.

The Church may distinguish its position towards other religions as an institution and a diplomatic entity without limiting the "people of God" to witness to others their salvation in Jesus.

Followers of Hinduism “contemplate the divine mystery and express it through an inexhaustible abundance of myths and through searching philosophical inquiry. They seek freedom from the anguish of our human condition either through ascetical practices or profound meditation or a flight to God with love and trust” (NA 2.2).

Buddhism, “in its various forms [it] realizes the radical insufficiency of this changeable world; it teaches a way by which men, in a devout and confident spirit, may be able either to acquire the state of perfect liberation, or attain, by their own efforts or through higher help, supreme illumination” (NA 2.2). ...

It would be heretical to assert that there is no truth outside the Church. Eastern religions have many good willed people seeking Truth who have not been authentically exposed to the Truth of Jesus. For how many futile years did the Spaniards try to evangelize the Aztecs before Our Lady of Guadalupe appeared. One of the factors in the 9 million conversions was the Aztec symbolism on the Tilma. Our Lady apparently had no trouble connecting the Truth of the Gospel to aspects of truth in the Aztec religion. We doubt she would use evil symbols on the Tilma. This is not syncretism. It's evangelization using symbols that the people understand.

In the Decree On Religious Liberty Dignitatis Humanae (DH), a concept of “religious liberty” is affirmed which does not seem to distinguish itself from the secular concept of the same, which is the fruit of the idea of tolerance, the origins of which are in Deism and the Enlightenment.

Decree On Ecumenism - Unitatis Redintegratio 3.4: considers “separated Churches and Communities,” notwithstanding their “deficiencies,” to be true and proper “means of salvation which derive their efficacy from the very fullness of grace and truth entrusted to the Church”