There was an interesting conversation on The Religion Report the other day about this very issue and they coined it in terms of relativism versus inclusivism. See the transcript and scroll down to about two thirds where David Rutledge is talking to Kath Engebretson:

David Rutledge:You also talk about relativism, and this is a related malaise for you, is this idea that whatever works for you is OK, you know, this is my truth, that’s your truth; you can’t judge other faiths by your own standards. Now are you saying that this mindset doesn’t promote good interfaith education, where from another perspective it might look as though that mindset is actually very tolerant and open, and inclusive. Why is relativism such a bad thing in interfaith education

Why’s this a problem? Because relativism is about ending the conversation. It’s the same as saying: let’s not talk about it. Or let’s agree not to be friends. It puts a blanket over the differences and tries to pretend they are not there: that can only end in problems down the line. It also means that we can’t critically engage with another faith. An important aspect of any human relationship is that we learn about ourselves and can be challenged to change. A better approach says Engebretson is called inclusivism and was written about by two theologians: Hans Kung and Karl Rahner.

Inclusivism I think means that I can still share in the goodness and truth of your religion, but coming from a committed stance in my own, and knowing what it is that attracts me and keeps me in my own religion, with an openness to learn how I can grow, through engagement with people in other traditions. So it’s a very far cry from relativism.

But this quickly leads to a less appealing discussion, the idea of the “Anonymous Christian” which is the idea that people in other faiths are saved by Christ, they just don’t know it. Engebretson is uncomfortable with that idea and so am I because it is almost going full circle back to the original problem of relativism. I think the problem is that interfaith communication is always going to have tension, it is never at peace but inclusivism means we can acknowledge the tension and still converse peacefully.