Evaluating a friend's argument for Christianity as the only true religion

¶ … friend who attempted to convince me that Christianity was the only "true religion." He based his argument upon several quotations from the Bible, one of which holds that human beings are only "saved" by Jesus Christ, and by believing in him. Another quotation encourages Christ's followers to evangelize the rest of the world. My friend bases his religious philosophy and beliefs on these two biblical principles. I order to convince me, he attempted to use the emotional and spiritual fulfillment that he and millions of others gain from adhering to the religion.

My problem, from a logical point-of-view, is that he is unable to base his argument on empirical evidence. Firstly, the Bible has been written millennia ago, by several people. Simply because it states in one verse that the Holy Spirit inspired the words, does not mean that this applies to all the books. Furthermore, history has proved several cases of tampering with this religious tome, making it somewhat more than unreliable in a concrete sense. While the Bible may therefore be of great literary and spiritual value, I hardly think it can be used as evidence for justifying the eradication of all other religions in favor of one.

As for his second argument, my friend bases this on arbitrary emotion rather than empirical evidence. He has not conducted any research to measure the level of satisfaction or the exact number of adherents experiencing this level of satisfaction as opposed to other religions. In my experience, religion in general provides its adherents with a sense of spiritual satisfaction. This does not apply only to Christianity.