No. You are wrong.
What is the source of your quote?"
Pope Eugene IV, Cantate Domino, 1441, and infallible declaration of the supreme magisterium of the Catholic Church.
It does not state that one must formally be a member of the Church.
Not my problem.
This quote is particularly false:
"and that no one, whatever almsgiving he has practiced, even if he has shed blood for the name of Christ, can be saved, unless he has remained in the bosom and unity of the Catholic Church."
So you just up and figure the Pope, while speaking ex cathedra, spoke falsely?
Father Feeney was condemned by Pius XII, in 1946, for just such a position. I will post the letter from the Holy Office tomorrow.