J.R.R. Tolkien and C. S. Lewis shared a friendship of over 40 years that affected not only their literary style but faith as well. Tolkien guided Lewis to convert to Christianity and Lewis encouraged Tolkien to write fantasies. As writers, both men introduced basic Christian themes and principles into their works for their readers. For them it was by means of God``s Natural Law as revealed in nature that even the most ancient of myths contained some traces of the Gospel, although in partial and impersonal form. Without a belief in Natural Law, humans are condemned to live in society governed only by power and self-interest at the expense of civility and novelty. Thus in their fiction, letters and critical writings, Tolkien and Lewis revealed their belief that Natural Law provides an objective standard of morality. Tolkien traced the natural law in the fairy tales, which has the characteristics of the recovery, escape and comfort. Lewis tries to search the commomalities in the Christianity and Tao in old China over era, region and culture. Tolkien and Lewis shared the congenial spirits both in literature and faith.