My friends, I believe a particularly urgent task of religion today is to unveil the vast potential of human reason, which is itself God’s gift and which is elevated by revelation and faith. Belief in the one God, far from stunting our capacity to understand ourselves and the world, broadens it. Far from setting us against the world, it commits us to it.
We are called to help others see the subtle traces and mysterious presence of God in the world which he has marvellously created and continually sustains with his ineffable and all-embracing love. Although his infinite glory can never be directly grasped by our finite minds in this life, we nonetheless catch glimpses of it in the beauty that surrounds us. When men and women allow the magnificent order of the world and the splendour of human dignity to illumine their minds, they discover that what is "reasonable" extends far beyond what mathematics can calculate, logic can deduce and scientific experimentation can demonstrate; it includes the goodness and innate attractiveness of upright and ethical living made known to us in the very language of creation.
This insight prompts us to seek all that is right and just, to step outside the restricted sphere of our own self-interest and act for the good of others. Genuine religion thus widens the horizon of human understanding and stands at the base of any authentically human culture. It rejects all forms of violence and totalitarianism: not only on principles of faith, but also of right reason. Indeed, religion and reason mutually reinforce one another since religion is purified and structured by reason, and reason’s full potential is unleashed by revelation and faith.
A lot of this depends on what the Pope means by religion. Of course, he said "genuine religion," which leaves him the usual opening of the ideologue. You know how this works. The Marxist-Leninist looks upon the disasters of the Soviet Union and says it wasn't "real" Marxism. Libertarians dodge the carnage of every business cycle and tell us that depressions are proof that "real" capitalism hasn't been in effect. So Benedict would probably tell you, and mean it, that the Crusades didn't represent "real" religion. That might even apply to the Inquisition. Apologists for Islam adopt the same strategy.
As for his last claim, it depends on what Ratzinger means by "reason's full potential," and he hinted at that earlier in the excerpt. In his view, reason needs to get beyond math, logic and science, and must do so for the sake of "upright and ethical living," which in his view requires taking something on faith. I suppose that faith in man in general is a precondition of civilization, but Benedict, being a Catholic, has to bring revelation into it. It's one thing to have faith in people, another to accept on their word alone that some scripture is the indisputable dictate of the ruler of the universe. So it sounds like the Pope believes that reason achieves its full potential by contradicting itself. Or maybe his remarks were mistranslated, but I doubt this.