I do suppose it does depend on the precise meanings you are using for your phrase “Christless”. If it means that Christ Himself is not a significant theme of a particular church, then the Catholic Church, being (I believe) the one true Church He Himself instituted and sent the Spirit to guide unto all Truth, is immune to this. She cannot - by virtue of that divine appointment - deny the central role of Christ, nor can She formally decree that something other than He is more central to our faith. She cannot because the Spirit will not allow it, not because the Church has the most faithful people within it - very faithful that many of them indeed are.
In terms of Islam and Judaism, you’ll have to point me toward any documentation you are concerned about regarding them. Suffice it to say that the Church, outside of it’s core teaching of the salvation through Jesus Christ, does continue to clarify its historical position on the salvation of those who do not know Christ. From the CCC:
“Outside the Church there is no salvation”
846 How are we to understand this affirmation, often repeated by the Church Fathers? Re-formulated positively, it means that all salvation comes from Christ the Head through the Church which is his Body:
Basing itself on Scripture and Tradition, the Council teaches that the Church, a pilgrim now on earth, is necessary for salvation: the one Christ is the mediator and the way of salvation; he is present to us in his body which is the Church. He himself explicitly asserted the necessity of faith and Baptism, and thereby affirmed at the same time the necessity of the Church which men enter through Baptism as through a door. Hence they could not be saved who, knowing that the Catholic Church was founded as necessary by God through Christ, would refuse either to enter it or to remain in it.
847 This affirmation is not aimed at those who, through no fault of their own, do not know Christ and his Church:
Those who, through no fault of their own, do not know the Gospel of Christ or his Church, but who nevertheless seek God with a sincere heart, and, moved by grace, try in their actions to do his will as they know it through the dictates of their conscience - those too may achieve eternal salvation.
848 “Although in ways known to himself God can lead those who, through no fault of their own, are ignorant of the Gospel, to that faith without which it is impossible to please him, the Church still has the obligation and also the sacred right to evangelize all men.”
This is not an expression or declaration that explicit faith in Christ is unnecessary…rather it is an acknowledgement that implicit faith in Christ for those ignorantly unaware of the Gospel throughout their entire lives can (not necessarily will) ultimately save them. For those who become aware of the Gospel, this explicit faith in Christ is indeed required. This explicit faith, mind you, also does not guarantee heaven. That issue delves into “faith alone” concepts which I’m sure you’d rather not get into here.
Blessings.
I know many Protestants who do not adhere to the doctrinal distinctives of the Protestant Reformation and believe that you can be saved apart from faith in Jesus Christ. Many will say that your are judge according to the light that you have apart from special revelation (Christ and Him crucified). But when you look at Romans 1 and 2, the light of general revelation and conscience condemns us universally as individuals. Since we agree in original sin, then apart from Christ we are all lost and eternally condemned as descendants of Adam (Rom 5). It seems the Catholic Church holds a similar position that a peson can be reconciled to God apart from hearing and receivng the gospel. I personally cannot understand this concept, since if a proclamation of the gospel (Christ and Him crucified) is not necessary revelation to be saved or reconciled to God, then the good news (gospel) turns into an accountable bad news. People are condemned by rejection of Jesus Christ as compared to already being condemned before hearing the good news of Jesus Christ. The gospel is always good news about God rescuing sinners from their already condemned condition. John chapter 3 is a solid chapter to study what I am saying.
Here is a portion of the Catechism on Muslims. It’s hard to believe that this has always been the historic Catholic position in regards to Muslims.
Part 1, Section 2, Chapter 3, Article 9, Paragraph 3, SubSection 3, Heading 4
841 The Church’s relationship with the Muslims. “The plan of salvation also includes those who acknowledge the Creator, in the first place amongst whom are the Muslims; these profess to hold the faith of Abraham, and together with us they adore the one, merciful God, mankind’s judge on the last day.” 330
I can be interpreted as a Christless Christianity position since the faith of Abraham is the gospel about the coming redeemer. Even Job knew that his redeemer lived.
Galatians 3:8
And the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel beforehand to Abraham, saying, “In you shall all the nations be blessed.”
Here appears to be another applicable scripture between Christians (children of promise) and Muslims:
Example of Hagar and Sarah
21 Tell me, you who desire to be under the law, do you not listen to the law? 22 For it is written that Abraham had two sons, one by a slave woman and one by a free woman. 23 But the son of the slave was born according to the flesh, while the son of the free woman was born through promise. 24 Now this may be interpreted allegorically: these women are two covenants. One is from Mount Sinai, bearing children for slavery; she is Hagar. 25 Now Hagar is Mount Sinai in Arabia; [5] she corresponds to the present Jerusalem, for she is in slavery with her children. 26 But the Jerusalem above is free, and she is our mother. 27 For it is written,
“Rejoice, O barren one who does not bear;
break forth and cry aloud, you who are not in labor!
For the children of the desolate one will be more
than those of the one who has a husband.”
28 Now you, [6] brothers, like Isaac, are children of promise. 29 But just as at that time he who was born according to the flesh persecuted him who was born according to the Spirit, so also it is now. 30 But what does the Scripture say? “Cast out the slave woman and her son, for the son of the slave woman shall not inherit with the son of the free woman.” 31 So, brothers, we are not children of the slave but of the free woman.
Gal 4