In a papal Bull, Pope Boniface VIII (1302) made dogmatic propositions on the unity of the Church, the necessity of belonging to it for the attainment of eternal salvation, the position of the Pope as supreme head of the Church, and the duty thence arising of submission to the Pope in order to belong to the Church and thus to attain salvation. The document seems to fulfill all the requirements of an infallible papal statement as laid down in 1871 at the First Vatican Council. The final line reads: "we declare, we proclaim, we define that it is absolutely necessary for salvation that every human creature be subject to the Roman Pontiff".
This teaching was largely repeated on a number of later occasions by both councils and popes, notably by the Council of Florence (Decree for the Jacobites, 1442): "(The Holy Roman Church).. firmly believes, professes and "(The Holy Roman Church).. firmly believes, professes and preaches that "no-one remaining outside the Catholic Church, not only pagans", but also Jews, heretics or schismatics, can become partakers of eternal life; but they will go to the "eternal fire prepared for the Devil and his angels" (Mt. 25:41), unless before the end of their life they are received into it".
The statements concerning the relations between the spiritual and the secular power are of a purely historical character, so far as they do not refer to the nature of the spiritual power, and are based on the actual conditions of medieval Europe. These statements have been used in a manner not justified by their content.
As it stands, this doctrine has been repudiated by the modern Catholic Church. Even in the 19th century, Pius IX was clear that innocent people of goodwill could be saved.
The Second Vatican Council specifically asserts that people in all religions can be saved: Finally, those who have not yet received the Gospel are related to the People of God in various ways. There is, first, that people to which the covenants and promises were made, and from which Christ was born according to the flesh (cf. Rom. 9:4-5): in view of the divine choice, they are a people most dear for the sake of the fathers, for the gifts of God are without repentance (cf. Rom. 11:29-29). But the plan of salvation also includes those who acknowledge the Creator, in the first place amongst whom are the Moslems: 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. Nor is God remote from those who in shadows and images seek the unknown God, since he gives to all men life and breath and all things (cf. Acts 17:25-28), and since the Savior wills all men to be saved (cf. 1 Tim. 2:4). 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 many achieve eternal salvation. Nor shall divine providence deny the assistance necessary for salvation to those who, without any fault of theirs, have not yet arrived at an explicit knowledge of God, and who, not without grace, strive to lead a good life. Whatever good or truth is found amongst them is considered by the Church to be a preparation for the Gospel and given by him who enlightens all men that they may at length have life.