I. THE DESIRE FOR GOD
27 The desire for God is written in the human heart, because man is created by God and for God; and God never ceases to draw man to himself…
From one ancestor [God] made all nations to inhabit the whole earth, and he allotted the times of their existence and the boundaries of the places where they would live, so that they would search for God and perhaps grope for him and find him - though indeed he is not far from each one of us. For "in him we live and move and have our being."2
29 But this “intimate and vital bond of man to God” (GS 19 § 1) can be forgotten, overlooked, or even explicitly rejected by man.3 Such attitudes can have different causes: revolt against evil in the world; religious ignorance or indifference; the cares and riches of this world; the scandal of bad example on the part of believers; currents of thought hostile to religion; finally, that attitude of sinful man which makes him hide from God out of fear and flee his call.4
30 "Let the hearts of those who seek the LORD rejoice."5 Although man can forget God or reject him, He never ceases to call every man to seek him, so as to find life and happiness. But this search for God demands of man every effort of intellect, a sound will, “an upright heart”, as well as the witness of others who teach him to seek God.
You are great, O Lord, and greatly to be praised: great is your power and your wisdom is without measure. And man, so small a part of your creation, wants to praise you: this man, though clothed with mortality and bearing the evidence of sin and the proof that you withstand the proud. Despite everything, man, though but a small a part of your creation, wants to praise you. You yourself encourage him to delight in your praise, for you have made us for yourself, and our heart is restless until it rests in you.6
II. WAYS OF COMING TO KNOW GOD
31 Created in God’s image and called to know and love him, the person who seeks God discovers certain ways of coming to know him. These are also called proofs for the existence of God, not in the sense of proofs in the natural sciences, but rather in the sense of “converging and convincing arguments”, which allow us to attain certainty about the truth. These “ways” of approaching God from creation have a twofold point of departure: the physical world, and the human person.
32 The world: starting from movement, becoming, contingency, and the world’s order and beauty, one can come to a knowledge of God as the origin and the end of the universe.
As St. Paul says of the Gentiles: For what can be known about God is plain to them, because God has shown it to them. Ever since the creation of the world his invisible nature, namely, his eternal power and deity, has been clearly perceived in the things that have been made.7
36 "Our holy mother, the Church, holds and teaches that God, the first principle and last end of all things, can be known with certainty from the created world by the natural light of human reason."11 Without this capacity, man would not be able to welcome God’s revelation. Man has this capacity because he is created “in the image of God”.12
37 In the historical conditions in which he finds himself, however, man experiences many difficulties in coming to know God by the light of reason alone:
Though human reason is, strictly speaking, truly capable by its own natural power and light of attaining to a true and certain knowledge of the one personal God, who watches over and controls the world by his providence, and of the natural law written in our hearts by the Creator; yet there are many obstacles which prevent reason from the effective and fruitful use of this inborn faculty. For the truths that concern the relations between God and man wholly transcend the visible order of things, and, if they are translated into human action and influence it, they call for self-surrender and abnegation. The human mind, in its turn, is hampered in the attaining of such truths, not only by the impact of the senses and the imagination, but also by disordered appetites which are the consequences of original sin. So it happens that men in such matters easily persuade themselves that what they would not like to be true is false or at least doubtful.13
38 This is why man stands in need of being enlightened by God’s revelation, not only about those things that exceed his understanding, but also “about those religious 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 men with ease, with firm certainty and with no admixture of error”. 14