First, the Catechism does address the Church’s relationship with the Jewish people in the immediate, two preceeding paragraphs:
839 "Those who have not yet received the Gospel are related to the People of God in various ways."325
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,326 "the first to hear the Word of God."327 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”,328 "for the gifts and the call of God are irrevocable."329
840 And when one considers the future, God’s People of the Old Covenant and the new People of God tend towards similar goals: expectation of the coming (or the return) of the Messiah. But one awaits the return of the Messiah who died and rose from the dead and is recognized as Lord and Son of God; the other awaits the coming of a Messiah, whose features remain hidden till the end of time; and the latter waiting is accompanied by the drama of not knowing or of misunderstanding Christ Jesus.
The Catechism in this section is about what the Catholic Church is, and moves from there outward, to non-Catholic Christians, to Jews, to Muslims, to others.
What would be incorrect is to think the Catechism is saying that all roads are equal paths to God: it does NOT say this. And neither does it mean that Islam teachings are salvific: they are not.
It’s recognizing what common truths we do have with other faiths. It doesn’t mean other faiths have the fullness of truth, and it doesn’t teach that other faiths have truths that are sufficient. Islam does recognize the truth of monotheism. It recognizes that God is transcendant above all and is the creator of all. Islam is neither atheist, deist, or pantheist, but truly monotheist. In respect to what can naturally be known according to looking at nature (in contrast to divine revalation), the monotheistic faiths have much in common. Even within divine revelation, they also have some things in common, from recognizing God’s relationship to Adam, Noah, Abraham, and even Moses. Muslims even praise Jesus as among the greatest of those who’ve known God and who will come again (though we know this isn’t sufficient). They are a people descended from Abraham’s son, Ishmael. Now, we certainly have many differences and disagreements. That includes many profound differences in theology and ideas of salvation. But we do have some common ground with them, which the Catechism is recognizing. But it’s not calling it equal or a faith sufficient for salvation in itself. As noted, if you read the entire section, the Church is explaining its relationship with different groups in an ever broadening fashion.
It would help to read the entire section. Here is a little more (but not all)
842 The Church’s bond with non-Christian religions is in the first place the common origin and end of the human race:
All nations form but one community. This is so because all stem from the one stock which God created to people the entire earth, and also because all share a common destiny, namely God. His providence, evident goodness, and saving designs extend to all against the day when the elect are gathered together in the holy city. . .331
843 The Catholic Church recognizes in other religions that search, among shadows and images, for the God who is unknown yet near since he gives life and breath and all things and wants all men to be saved. Thus, the Church considers all goodness and truth found in these religions as "a preparation for the Gospel and given by him who enlightens all men that they may at length have life."332
844 In their religious behavior, however, men also display the limits and errors that disfigure the image of God in them:
Very often, deceived by the Evil One, men have become vain in their reasonings, and have exchanged the truth of God for a lie, and served the creature rather than the Creator. Or else, living and dying in this world without God, they are exposed to ultimate despair.333
845 To reunite all his children, scattered and led astray by sin, the Father willed to call the whole of humanity together into his Son’s Church. The Church is the place where humanity must rediscover its unity and salvation. The Church is “the world reconciled.” She is that bark which “in the full sail of the Lord’s cross, by the breath of the Holy Spirit, navigates safely in this world.” According to another image dear to the Church Fathers, she is prefigured by Noah’s ark, which alone saves from the flood.334
The paragraphs after this explain the Church’s view of what it means for there to be no salvation outside the Church. Did you read only paragraph 841 or the whole section? Context… context… context…
vatican.va/archive/ccc_css/archive/catechism/p123a9p3.htm
