Keeler admits that religion is one of the main barriers to world peace. He says leaders have addressed this in one of 3 ways: outlaw religion, condemn religion, or privatize religion. He believes these are all ineffective strategies. His primary response is to affirm Christianity's exclusive message and to contend that the fundamentals of Christianity, if followed, will lead better than any other religion to "humble, peace-loving behavior".
As a believer, I am troubled by the rise of fundamentalism and violent behavior we have seen around the world. As we have become a global community, there are more opportunities for bumping up against others with different belief systems. I'm not sure that the only answer to increasing peace is to assert Christianity's superiority in creating it. The truth is that it is difficult for human beings to maintain peace as long as there is "us" and "them". It is even more difficult when we don't really know "them". The truth is that there is a long history, extending from the Old Testament through the New Testament, where there are marked distinctions between "us" and "them", leading to genocide in the Old Testament and disfellowship in the New Testament.
I respect the fact that Keller doesn't apologize for claiming that Christian beliefs are different and superior to others. I think it is dishonest to claim belief in Jesus as the only way to salvation while affirming that every other religion also has it right. However, I do think some humility is in order when evaluating our own beliefs. The truth is that we are more critical of others' belief systems than we are of our own. If our belief system is true, then it should withstand the scrutiny that we apply to other religions.