Especially under the imposing influence of Augustine and his anti-Pelagian polemic, and then in the heat of battle against the "paganism” of Islam, the prevalent attitude toward other religions from the fifth century through the Middle Ages (even for Aquinas) was that "outside the church there is no salvation." The Council of Florence (1442) officially declared 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."
What [later] took place was a significant shift in Catholic theology from an exclusive to an inc1usive understanding of the church as the sole channel of grace. In other words, Catholic belief moved from holding "outside the church no salvation” to "without the church no salvation." During the first half of the twentieth century, Catholic theologians came up with ingenious concepts to include within the church any trace of salvation outside it: saved non-Christians belonged to the "soul” of the church; they were "attached," "linked," "related” to the church; they were members "imperfectly," "tangentially," "potentially."
Historians often forget that this positive shift in Catholic attitudes toward "pagans” did not include a more positive attitude toward pagan religions. Very few theologians ventured the assertion that universally available grace might be available through the religions. The experience of God’s grace, always an ecclesial affair for Catholics, was evidently a private affair for pagans.
Vatican Council II continued the inclusive ecclesiocentrism of the previous period. While the council fathers reaffirmed that the church is necessary for salvation, they also, as it were, extended the universal possibility of salvation--even atheists could be saved. Yet the council, as is well known, took a definitely new turn when, for the first time in the history of official church statements, it praised individual world religions for the way they reflect "that Truth which enlightens every person."
The majority of Catholic thinkers interpret the conciliar statements to affirm, implicit~ but clearly, that the religions are ways of salvation. These theologians endorse the theology of religions elaborated by Karl Rahner, whose thought so strongly influenced the council's deliberations. In Rahner, and in his endorsers, we see another radical change in Catholic theology of religions. The main ingredients in Rahner's optimistic assessment of other religions are well known. They are two: God’s universal salvific will (grounding what Rahner terms a "salvific optimism" for all humanity) and humanity's essentially social nature. Combining the two ingredients: if God wills to grant grace to every person, this grace must take on a sociohistorical "body" in order to be really available; and among the most likely mediating bodies for grace are the religions. The religions therefore are or can be "grace-filled” ways of salvation and are "positively included in God’s plan of salvation."
What enables Rahner to draw this conclusion is his subtle but significant shift from ecclesiocentrism to Christocentrism. This shift is embodied in Rahner’s much-discussed model of anonymous Christianity (which, as his critics often forget, he intended only for Christian consumption, not for proclamation to outsiders). The model’s first intent is to remind Christians that God’s saving presence "is greater than man and the Church"; grace can, as it were, float free of the visible church and incarnate itself in other words and sacraments. But for Rahner, if grace is not bound to the church, it is bound to Christ. Jesus of Nazareth is the constitutive cause of all salvation. As the full and final manifestation of God’s saving presence in history, he is both the cause (final and the goal) of every experience of God. Grace, therefore, is always Christ’s, always oriented toward Christ and toward Christ’s continued embodiment in the church. (In this sense, Rahner continues to claim the "necessity” of the church.) In the final analysis, then, the religions are incomplete without Christ; they must be fulfilled in him and his church; they are a preparation for the gospel. The missionary mandate remains intact and is reinforced. Vatican II’s statements on other religions, as interpreted by Rahner, embody the mainline view of Roman Catholic theologians, even though they may not expressly use the model of anonymous Christianity. Edward Schillebeeckx, Pietro Rossano, Avery Dulles, Richard McBrien, even Pierre Teilhard de Chardin affirm the universality of Christ and his grace and the religions as mediators of that grace." Because these theologians continue to hold to Christ as the one Savior and constitutive cause of salvation, they view the religions are already partially containing Christ’s grace, but as incomplete until fully incorporated into Christ and his church.
Although most contemporary Roman Catholic theologians readily accept the basics of the mainline approach to other religions, many are uneasy with the way it seems to judge religions before really listening to them, especially by predefining them as anonymous Christians. This uneasiness has given rise to another realignment in Catholic attitudes toward religions; there is a shift beyond Vatican II and Rahner, toward a clearer recognition of the independent value and enduring mission of other faiths. The underlying, often implicit, theological foundation for this shift is a new understanding of Christ's (and the church's) salvific role. Hans Kung speaks for many in his criticism of the anonymous-Christianity model. For Kung, this theory is but a "theological fabrication,” intended to save the "infallible formula” of outside-the-church-no-salvation.
Knitter, P. "Roman Catholic Approaches to Other Religions: Developments and Tension," International Bulletin of Missionary Research, 8 (1984), pp. 50ff.