The Jews, in their Talmud, teach that Jesus was the bastard son of a harlot. The Muslims teach that he was a prophet but, otherwise, a mere man.
Neither belief is true. Nor are these religions true.
What we as Catholics should do, is pray for the souls of Jews, Muslims, Protestants and others – but we should not make the mistake of believing they have a “part” of the true religion. Truth is absolute. A half truth is a lie. Christ founded his Church, not churches and, all who will be saved, must come into the Church.
“It is, therefore, the Catholic Church alone which retains true worship. This is the fountain of truth; this, the domicile of faith; this, the temple of God. Whoever does not enter there or whoever does not go out from there, he is a stranger to the hope of life and salvation. . . . Because, however, all the various groups of heretics are confident that they are the Christians and think that theirs is the Catholic Church, let it be known that this is the true Church, in which there is confession and penance and which takes a health-promoting care of the sins and wounds to which the weak flesh is subject” (Divine Institutes 4:30:11–13 [A.D. 307]). --Lactantius
“If someone from this people wants to be saved, let him come into this house so that he may be able to attain his salvation. . . . Let no one, then, be persuaded otherwise, nor let anyone deceive himself: Outside of this house, that is, outside of the Church, no one is saved; for, if anyone should go out of it, he is guilty of his own death” (Homilies on Joshua 3:5 [A.D. 250]). --Origen
catholic.com/library/Salvation_Outside_the_Church.asp
By worshiping with Muslims or Jews you are, in effect, saying “Your religion is as good as ours.” But Christ said, “No one comes unto the Father but by me.” Both the Jewish and Muslim religions deny that Christ is God, therefore they deny Christ.
Now, I do believe, that those in other religions who are
invincibly ignorant of the true Faith
can be saved by God’s grace – but they’re saved despite their religion, not because of it.
"The case of heathens differs considerably from that of baptized Protestants. Heathens who are in error inculpably, and serve God to the best of their ability, according to the light which they possess, and are ready to do all that Heaven may desire from them, will certainly be saved. They may never receive the baptism of water, but for them what is called in the Catholic Church the baptism of desire, is sufficient. Their efforts to please God include the desire to know the true faith, and willingness to embrace it; and as to sanctifying grace, which is also necessary for salvation, God, who is unwilling that men should perish when they do their utmost to please Him, infuses into their souls, in the course of their lives, or at the moment of their death, the same sanctifying grace that is conferred by the baptism of water. If they fall into mortal sin, they may receive the grace to elicit an act of perfect contrition, and thereby obtain forgiveness. Their salvation is not according to the ordinary course of Providence, but the result of an extraordinary grace, conferred in view of the merits of Christ. By the baptism of desire they become members of the true Church of Christ, the Catholic Church, and are saved only as members of her communion.
In other words, there is only one way to heaven, but there are several ways that lead to the Catholic Church, for, besides the baptism of water, there is the baptism of blood, or martyrdom suffered by an unbaptised person for the faith of Christ, and the baptism of desire, of which I have just spoken. How many are saved by the baptism of desire, whether they are few or numerous, is known to God alone; we may cheerfully leave it in the hands of God, whose boundless mercy extends to every human soul, and never allows one to perish except through its own grievous fault…"
From “Protestantism and Infidelity” by F. X. WENINGER. D.D
bliz.org/newprot.html
Charity and understanding should be extended to those in other religions – but it should not be extended to their religions. We should have intolerance for false religions – and no religion can be more false than one that denies that Jesus Christ is God and the eternal Son of the God.
May God be with you