christianity is exclusive

I like Tim Keller's reply to the argument that Christianity and in particular the concept of hell is exclusive as compared to other more tolerant perspectives.

Nothing is more characteristic of the modern mindset than the statement: "I think Christ is fine, but I believe a devout Muslim or Buddhist or even a good atheist will certainly find God." A slightly different version is: "I don't think God would send a person who lives a good life to hell just for holding the wrong belief." This approach is seen as more inclusive.

In preaching about hell, then, I need to counter this argument:

The universal religion of humankind is: We develop a good record and give it to God, and then he owes us. The gospel is: God develops a good record and gives it to us, then we owe him (Romans 1:17). In short, to say a good person, not just Christians, can find God is to say good works are enough to find God. You can believe that faith in Christ is not necessary or you can believe that we are saved by grace, but you cannot believe in both at once. So the apparently inclusive approach is really quite exclusive. It says, "The good people can find God, and the bad people do not." But what about us moral failures? We are excluded. The gospel says, "The people who know they aren't good can find God, and the people who think they are good do not." Then what about non-Christians, all of whom must, by definition, believe their moral efforts help them reach God? They are excluded. So both approaches are exclusive, but the gospel's is the more inclusive exclusivity. It says joyfully, "It doesn't matter who you are or what you've done. It doesn't matter if you've been at the gates of hell. You can be welcomed and embraced fully and instantly through Christ."