If Christians cannot live in interfaith spaces, then I find it hard to see how Christ can be proclaimed among the nations of the world. If Christians freak out at walking alongside those with different faith commitments or worldviews, then I see no reason why anyone else would want to know about the gospel.
Is Jesus so paranoid that He crumbles in the face of religious plurality? Are we who are abiding in Christ so flimsy we recoil with fear at anything that does not resemble the Anglo-Americanism we have taken to be Christianity? Do we persist in labeling Asian meditation as "mind-emptying demonic possession" without even an iota of knowledge about meditation? Are we so insecure and bigoted as to eschew any language that is not English, Greek, or Hebrew when we talk about Christ in contexts outside the typical operational one that every church plucks out of the neoliberal corporatist handbook? Is present-day evangelicalism nothing more than Pharisaic legalism in Christian gloss? Is it such a bad thing that an atheist with hospitality for diverse views including exclusivist evangelicalism is appointed president of Harvard's Chaplain Group?
It is not biblical to confuse and conflate human empire with God's kingdom. Christendom as a projection of empire is dead and gone, for the better in my view. The hypocrisy galore we normally call "church" fails to convince me why I would want to have anything to do with it. As a Reformed evangelical, I am not universalist but particularist. I see Jesus as the exclusive Saviour. But this does not prevent me from deep interspirituality and hospitality in the context of pluralism. I don't think Jesus has a problem with that.
I think Keller is right in saying this. But I would go further in valorizing the plurality of world faiths as legitimate expressions of God’s common grace no matter the distortions and errors in some aspect or another. For God is at work in all cultures including atheistic and secular ones, and it is incumbent on Christians to seek to understand and extract truth from culture no matter where we find them. For all truth is God’s truth, and truth can be found in all cultures.