1. The difficulties that sometimes accompany the development of evangelisation highlight a delicate problem whose solution should not be sought in purely historical or sociological terms: the problem of the salvation of those who do not visibly belong to the Church. We are not given the opportunity to scrutinise the mystery of divine action in minds and hearts, to assess the power of Christ's grace in taking possession, in life and in death, of those whom 'the Father has given Him', and whom He Himself has proclaimed that He does not want to 'lose'. We hear this repeated in one of the Gospel readings proposed for the Mass of the Dead (cf. Jn 6:39-40).
But, as I wrote in the Encyclical Redemptoris Missio, one cannot limit the gift of salvation "to those who explicitly believe in God and have entered the Church. If salvation is destined for all, it must be made concretely available to all'. And, admitting that it is concretely impossible for so many people to access the Christian message, I added: "Many people do not have the possibility of knowing or accepting the revelation of the Gospel to enter the Church. They live in socio-cultural conditions that do not allow it, and they have often been educated in other religious traditions" (Redemptoris Missio, 10).
We must recognise that to the extent that it is within the human capacity for foresight and knowledge, this practical impossibility would seem destined to last much longer, perhaps even until the final completion of the work of evangelisation. Jesus himself admonished that only the Father knows "the times and moments" fixed by him for the establishment of his Kingdom in the world (cf. Acts 1:7).
2. What I have said above, however, does not justify the relativistic position of those who believe that a way to salvation can be found in any religion, even independently of faith in Christ the Redeemer, and that inter-religious dialogue should be based on this ambiguous conception. This is not the Gospel-compliant solution to the problem of salvation for those who do not profess the Christian creed. Instead, we must maintain that the road to salvation always passes through Christ, and that therefore it is up to the Church and its missionaries to make him known and loved in every time, in every place and in every culture. Outside of Christ 'there is no salvation'. As Peter proclaimed before the Sanhedrin from the very beginning of the apostolic preaching: "There is no other name under heaven given to men in which it is appointed that we should be saved" (Acts 4:12).
Even for those who through no fault of their own do not know Christ and do not recognise themselves as Christians, the divine plan has provided a way of salvation. As we read in the conciliar Decree on missionary activity Ad Gentes, we believe that "God, through the ways he alone knows, can bring men who through no fault of their own ignore the Gospel" to the faith necessary for salvation (Ad Gentes, 7). Of course, the condition 'without their guilt' cannot be verified or appreciated by human evaluation, but must be left solely to divine judgement. This is why in the Constitution Gaudium et Spes the Council declares that in the heart of every man of good will "grace works invisibly", and that "the Holy Spirit gives everyone the possibility of coming into contact, in the way God knows, with the Paschal Mystery" (Gaudium et Spes, 22).
3. It is important to emphasise that the way of salvation taken by those who ignore the Gospel is not a way outside Christ and the Church. The universal salvific will is linked to the unique mediation of Christ. This is stated in the First Letter to Timothy: "God our Saviour, who wills that all men should be saved and come to the knowledge of the truth. For one is God, and one is the mediator between God and man, the man Christ Jesus, who gave himself a ransom for all" (1 Timothy 2: 3-6). Peter proclaims this when he says that "in no one else is there salvation", and calls Jesus the "head of the corner" (Acts 4:11-12), emphasising the necessary role of Christ as the foundation of the Church.
This affirmation of the "uniqueness" of the Saviour draws its origin from the very words of the Lord, who states that he came "to give his life as a ransom for many" (Mk 10:45), i.e. for mankind, as St Paul explains when he writes: "One died for all" (2 Cor 5:14 cf. Rom 5:18). Christ obtained universal salvation by the gift of his own life: no other mediator was established by God as Saviour. The unique value of the sacrifice of the Cross must always be recognised in the destiny of every man.
4. And since Christ works salvation through his mystical Body, which is the Church, the way to salvation is essentially linked to the Church. The axiom extra Ecclesiam nulla salus - "outside the Church there is no salvation" -, enunciated by St Cyprian (Epist 73,21: PL 1123 AB), belongs to the Christian tradition and was included in the Lateran Council IV (Denz.-S. 802), in the bull Unam Sanctam of Boniface VIII (Denz.-S. 870) and in the Council of Florence (Decretum pro Jacobitis, Denz.-S. 1351).
The axiom means that for those who are unaware that the Church was founded by God through Jesus Christ as necessary there is an obligation to enter and persevere in it in order to obtain salvation (cf. Lumen Gentium, 14). On the other hand, for those who have not received the proclamation of the Gospel, as I wrote in the Encyclical Redemptoris Missio, salvation is accessible through mysterious ways insofar as divine grace is bestowed upon them by virtue of Christ's redeeming sacrifice, without external adherence to the Church but always, nevertheless, in relationship with it (cf. Redemptoris Missio, 10). It is a "mysterious relationship": mysterious for those who receive it, because they do not know the Church and indeed sometimes externally reject it; mysterious also in itself because it is linked to the salvific mystery of grace, which entails an essential reference to the Church founded by the Saviour.
Salvific grace, in order to operate, requires an adhesion, a cooperation, a yes to the divine donation: and this adhesion is, at least implicitly, oriented towards Christ and the Church. Therefore one can also say sine Ecclesia nulla salus - "without the Church there is no salvation" -: adhesion to the Church - Mystical Body of Christ, however implicit it may be, is indeed mysterious, and constitutes an essential condition for salvation.
5. Religions can exert a positive influence on the destiny of those who belong to them and follow their instructions with sincerity of spirit. But if the decisive action for salvation is the work of the Holy Spirit, we must bear in mind that man only receives his salvation from Christ, through the Holy Spirit. It begins already in the earthly life, which grace, accepted and reciprocated, makes fruitful, in the evangelical sense, for earth and heaven.
Hence the importance of the indispensable role of the Church, which "is not an end in itself but fervently strives to be all of Christ, in Christ and for Christ, and all of men, among men and for men". A role that is therefore not "ecclesiocentric" as has sometimes been said: the Church does not exist or work for itself, but is at the service of a humanity called to divine filiation in Christ (cf. Redemptoris Missio, 19). It therefore also exercises an implicit mediation towards those who are ignorant of the Gospel.
However, this should not lead to the conclusion that its missionary activity is less necessary in such circumstances. Quite the contrary. In fact, those who ignore Christ, through no fault of their own, find themselves in a condition of darkness and spiritual famine with negative repercussions often also on a cultural and moral level. The Church's missionary action can provide them with the conditions for the full development of Christ's saving grace, by proposing full and conscious adherence to the message of faith and active participation in Church life in the sacraments.
This is the theological line taken from Christian tradition. The Magisterium of the Church has followed it in doctrine and practice as the path marked out by Christ himself for the Apostles and missionaries of all times.
[Pope John Paul II, General Audience 31 May 1995]