Regarding the dogma extra ecclesiam nulla salus, Fenton is most illuminating.
For one thing, he shows that the dogma is quite precise and emphatic. It regards fact, and not just “objective ideal.” He writes,
“No man can enjoy this fellowship apart from the Catholic Church. Those who enjoy the Communion of Saints either are actually members of the Catholic Church or really intend to become members. Thus those in the state of grace, the persons who derive the full benefit from their association with the Church triumphant and the Church suffering, possess that charity which demands the love of the brotherhood. Every person in the state of grace intends to live and to die within the unity of the Catholic Church, even though, for want of proper instruction, his intention should be merely implicit” (Essay entitled “The Communion of Saints and the Mystical Body.”)
Why so? Because the Church is the necessary means for salvation, contra certain erroneous readings of the dogma:
“If the way of salvation were really open to men in all religions or in all religious societies, then there would certainly be no valid reason for pouring out the best blood of the Catholic Church in the never-ending effort to plant the company of Christ among the peoples of the world. The missionary labors of the Catholic Church are expended, not to bring about a mere improvement in the condition of people who would have been in a position to be saved in any event, but actually to carry the message and the means of salvation to those who sit in darkness. The work of converting men to the Church of Christ aims not at bringing an easier way of salvation but at bringing the very hope of salvation to the beneficiaries of Catholic preaching” (essay entitled “Theological Proof for the Necessity of the Catholic Church: Part 1” — a must read essay, in three parts.)