Jesus' exclusive status was proven by the Incarnation and the Resurrection. Our salvation is God's gift, not the result of human effort. The Church's role is to proclaim this Good News and to challenge the world to respond.
Neomodernist theologians see this claim to a definitive role in salvation as "scandalous." Saying that to give such a prominent position to Jesus an obstacle to dialogue with other faiths. It prejudges the outcome of ecumenical talks by demoting other spiritualties to a lesser position. Similarly, Leonard Swidler, whom I discuss in Smoke, opines: "there is a deeper reality which goes beyond the empirical surface experiences of our lives, and for us Jesus is the bond-bursting means of becoming aware of that deeper reality (as for Buddhists it is Gautama)." This suggests that, while for Christians the way to the transcendent is through Jesus, for others it is through their own revered figures. Undoubtedly, from an empirical point of view, there is some truth to this. However, there seems to be much more implied here. Neomodernists like Swidler seem unwilling to assign any uniqueness to the revelation in Jesus Christ that could put it on a different level from that which comes from any other created person. Others would explicitly deny that in Jesus anything unique happened in the relationship between God and humanity or that this has universal significance in a way that no other event does. It is the reluctance to assert this distinctiveness that opens the way for syncretistic thinking. Christianity becomes only one way among many in which humanity has sought to make contact with the divine. Christianity is no longer the definitive way in which God made contact with humanity.
The New Testament shows that, from the beginning, the Church rejected the syncretistic approach. St. Paul’s Epistle to the Colossians is the first clear indication of the Church's early battle with syncretism. For the Apostle, Christian spirituality was built on the risen Christ, not created by merging other ideas and practices. Paul tells Christians not to be captivated by "an empty, seductive philosophy according to human tradition, according to the elemental powers of the world and not according to Christ" (Col. 2:8). As early as A.D. 70, then, the Catholic Church was cognizant that it had a unique identity that ruled its relationships with other spiritual traditions. It was on this basis that it dealt with the Judaism from which it emerged, the various mystery religions which abounded in Paul’s day, and emperor worship which anchored the Roman social and political order.