But there are people who, through no fault of their own, do not know Christ and his Church. They also are included in God's plan of salvation. There are, however, conditions. They must be sincere in their seeking of God. They must be open to the secret but real action of the Holy Spirit in them. They should follow their conscience in all matters of right and wrong. Because Christ has taken on human nature and somehow united himself with every man and woman, God can in ways known to him put people in link with the saving mysteries of Christ (cf. Gaudium et Spes, 22). He can give them the grace needed for salvation.
But to say that the followers of other religions can attain salvation under some conditions does not mean to ignore the fact that in these religions there ~re limits, errors and shadows. As St Paul says: "Very often, deceived by the Evil One, men have become vain in their reasonings, and have exchanged the truth of God for a lie, and served the creature rather than the Creator. Or else, living and dying in this world without God, they are exposed to ultimate despair" (Rom 1:21,25). This explains why the Catholic Church "painstakingly fosters her missionary work" (Lumen Gentium, 16) so that, becoming full members of the Church, people may have access to the fullness of the means of salvation, a fullness to be found only in the Church which is the ordinary means to salvation. The CCC therefore says: "To reunite all his children, scattered and led astray by sin, the Father willed to call the whole of humanity together into his Son's Church. The Church is the place where humanity must rediscover its unity and salvation. The Church is 'the world reconciled.' She is that bark which 'in the full sail of the Lord's cross, by the breath of the Holy Spirit, navigates safely in this world.' According to another image dear to the Church Fathers, she is prefigured by Noah's ark, which alone saves from the flood" (CCC 845; cf. also CDF, Dominus Jesus, 20-22). Cardinal Arinze Oct 26, 2000