Benedict concludes Part I of Christianity and the Crisis of Cultures with a chapter entitled "The Permanent Significance of the Christian Faith."
He begins by reminding us that the foregoing historical and philosophical critique of Enlightenment thought is not tantamount to a rejection of the Enlightenment and Modernity. On the contrary, Benedict reiterates a theme deeply entwined in the message of the Second Vatican Council, namely, that Christianity, as "the religion of the Logos "and" a religion in keeping with reason," shares much common ground with the best that Enlightenment thought had to offer. Christianity and Enlightenment have shared the aspiration to be "open to all that is truly rational." But again, Benedict cogently insists that their apparent irreconcilability is reducible to a disagreement about the nature and scope of human reason:
[T]he problem is whether the world comes from an irrational source, so that reason would be nothing but a "by-product" (perhaps even a harmful by-product) of the development of the world, or whether the world comes from reason, so that its criterion and its goal is reason. The Christian faith opts for this second thesis and has good arguments to back it up, even from a purely philosophical point of view, despite the fact that so many people today consider the first thesis the only "rational" and modern view. A reason that has its origin in the irrational and is itself ultimately irrational does not offer a solution to our problems. Only that creative reason which has manifested itself as love in the crucified God can truly show us what life is (p. 49).
Benedict holds that Christians must continue to engage a secularized culture with a vision of reality in which rational activity, human consciousness, and the experience of freedom, far from being understood as the bi-product of mindless biochemical evolution, are in fact the product of "creative reason", gifts of the Logos to humanity.
And on the basis of such a positive vision, and in the light of his foregoing commentary, Benedict ends Part I, with a challenge. He recalls that some Enlightenment thinkers responded to the religious and intellectual upheavals of their day by trying to shield the fundamental tenets of the moral life from similar scrutiny and upheaval by suggesting that "even if God did not exist" (etsi Deus non daretur) those moral tenets would still be true -- for all peoples, in all times and places. In the wake of the tragedies spawned by modern and contemporary God-less secularism, the Holy Father ends by suggesting that today secularists would be wise to do just the opposite, "to live as if God existed" (veluti si Deus daretur).
This is the advice Pascal gave to his non-believing friends, and it is the advice that I should like to give to our friends today who do not believe. This does not impose limitations on anyone's freedom; it gives support to all our human affairs and supplies a criterion of which human life stands sorely in need (pp. 51-52).