But if I can't trust my own thinking, of course I can't trust the arguments leading to Atheism, and therefore have no reason to be an Atheist, or anything else. It is only with the utmost care that humans can hope to arrive at the correct answer to even the most rudimentary problems. Furthermore, saying that it is necessary to believe in God to have faith in the reliability of thought is hardly a proof for God. It is no more than saying that you must have faith in Intel or Motorola in order to accept the results produced by your computer. Believing in God does nothing to resolve the essential question of the reliability of our perception of reality, which is really the question here.
Nature has for some reason programmed it that way.
Ultimately, Lewis's appeal to Christians lies in his defense of Christianity through the use of rational arguments. By not appealing to faith or the divine word of the Bible, Lewis strives to put Christianity, and therefore Christians, on the same intellectual levels with science and rationalists. This approach is soothing to believers suffering from feelings of inferiority, who rarely note that Lewis's logic immediately collapses under even the most cursory critique. Consequently, Lewis has become one of the most widely read Christian writers. He attempts to provide reason for faith.