There was some confusion in the comments of the the “Two True Religions” article. The gist of that article is that God established both Judaism and Catholicism. And that, because of the Sacraments, it is better to be Catholic than Jewish.
One of the commenters said that, "since there is one Plan of Salvation, therefore, there is only one True Religion."
The assumption is that Plan of Salvation means “religion”. If that were true, then, of course, that commenter would be correct.
But that assumption is wrong.
The Catholic Church nowhere defines the term, Plan of Salvation, to mean religion. In fact, it frequently identifies the “Jewish” religion and the “Catholic” religion. Using different modifiers. As we can see, here:
839 "Those who have not yet received the Gospel are related to the People of God in various ways."
The relationship of the Church with the Jewish People. When she delves into her own mystery, the Church, the People of God in the New Covenant, discovers her link with the Jewish People, "the first to hear the Word of God." The Jewish faith, unlike other non-Christian religions, is already a response to God's revelation in the Old Covenant. To the Jews "belong the sonship, the glory, the covenants, the giving of the law, the worship, and the promises; to them belong the patriarchs, and of their race, according to the flesh, is the Christ", "for the gifts and the call of God are irrevocable."
So, although there is one Plan of Salvation, that plan includes two, separate and true religions. One of them fulfilling the other.
In addition, the Catholic Bible refers to the Jew’s religion as opposed to the Revelation of Jesus Christ in the Church of God:
Galatians 1:12-14 Douay-Rheims 1899 American Edition (DRA)
12 For neither did I receive it of man, nor did I learn it; but by the revelation of Jesus Christ.
13 For you have heard of my conversation in time past in the Jews' religion: how that, beyond measure, I persecuted the church of God, and wasted it. 14 And I made progress in the Jews' religion above many of my equals in my own nation, being more abundantly zealous for the traditions of my fathers.
Therefore, both in the Catechism and in the Bible, the Catholic Church identifies the Jewish religion as distinct from the Catholic Faith.
The other commenter called it a heresy to say that there were two true religions and used this paragraph from the Catechism to support his contention:
2105 The duty of offering God genuine worship concerns man both individually and socially. This is "the traditional Catholic teaching on the moral duty of individuals and societies toward the true religion and the one Church of Christ." By constantly evangelizing men, the Church works toward enabling them "to infuse the Christian spirit into the mentality and mores, laws and structures of the communities in which [they] live." The social duty of Christians is to respect and awaken in each man the love of the true and the good. It requires them to make known the worship of the one true religion which subsists in the Catholic and apostolic Church. Christians are called to be the light of the world. Thus, the Church shows forth the kingship of Christ over all creation and in particular over human societies.
That does say that there is one true religion which subsists in the Catholic and Apostolic Church. But, does that imply that the Jewish religion was not established by God? No, it doesn’t. If it did, it would contradict paragraph 839, which I quoted above. Therefore, it does not deny that God established two true religions. The Jewish and the Catholic.
The Catholic Church has fulfilled the Jewish Covenant, and is today, the one true religion. But it was preceded by the Jewish faith, which was previously, the one true religion. And the non-Catholic Jews of today, have not accepted Jesus as Messiah but continue to wait for the Messiah. While we wait for His Second Coming.
Anyway, I hope that clarifies matters.