Parts 3 and 4 of our exploration of the Compendium of the Catechism of the Catholic Church...
How is it possible to know God with only the light of human reason?
Starting from creation, that is from the world and the human person, through reason alone one can know God with certainty as the origin and end of the universe, as the highest good and as infinite truth and beauty.
Is the light of reason alone sufficient to know the mystery of God?
In coming to a knowledge of God by the light of reason alone man experiences many difficulties. Indeed, on his own he is unable to enter into the intimacy of the divine mystery. This is why he stands in need of being enlightened by God’s revelation, not only about those things that exceed his understanding, but also about those religions and moral truths which of themselves are not beyond the grasp of human reason, so that even in the present condition of the human race, they can be known by all with ease, with firm certainty and with no admixture of error.