Okay: The plan of salvation also includes those who acknowledge the Creator, in the first place amongst whom are the Muslims
You need to interpret this according to Catholic teaching dating back to Aquinas and before, not according to anyone else's understanding.
It amounts to saying: "It's very nice that Muslims 'acknowledge the Creator'. We cannot say with certainty that God, who wills all men to be saved and come to knowledge of the truth, will not save some Muslims -- in spite of the errors they hold."
It is in no sense a claim that all Muslims are going to heaven. Don't you think we'd first have to decide that all Catholics are going to heaven ... yet we don't; the only Catholics the church teaches infallibly are saved are canonized saints.
And is it your contention that the Catholic Church assumes all Protestants are saved?
As I just explained, we don't assume that all Catholics are saved. (Haven't you ever read Dante's "Inferno," which depicts hell filled with wicked Popes and bishops?)
That you can be saved outside the Church?
Absolutely, positively, nobody will be saved outside the Catholic Church. Not Muslims, not Protestants, nobody.
That is not the same as saying that only people who profess Catholicism on earth will be saved.
It is the same as saying that there will not be a Muslim heaven, not a Baptist heaven, not a Jewish heaven. All religious disunity on earth is the consequence of sin. There is one "church" in heaven only, and it is universal ... the Greek word is "catholic".
"For the Father judges no one, but has committed all judgment to the Son, that all should honor the Son just as they honor the Father. He who does not honor the Son does not honor the Father who sent Him." - John 5:22-23Jesus tells us in direct language that only those that honor Him will honor God. If you do not acknlowedge and honor Jesus, you do not the same for God. Yet the Catechism says that is not the case, since Muslims honor the same God.
Note too that Jesus sits alone in judgement. Not God, not the Church. Jesus. Any claim of any other entity is heretical, and that includes the Church in its process of ex-communication.
Jesus said to him, "I am the way, the truth, and the life. No one comes to the Father except through Me." - John 14:6
Jesus then claims that the sole way to God is through Him. No other way works. Only through Jesus. How then, can you claim that Muslims will reach Heaven simply on the strength of their belief in the Creator? That is in direct contradiction of the Words of Christ.
Absolutely, positively, nobody will be saved outside the Catholic Church. Not Muslims, not Protestants, nobody... There is one "church" in heaven only, and it is universal ... the Greek word is "catholic".
Thus Protestants and Orthodox are all "catholic" as well, part of the universal Church?
Yes, the catholic (universal) Body of Christ. You can’t be saved outside of Christ but you can be saved outside of the Catholic Church. Most probably are. Members of the Body of Christ are in all kinds of churches.