26 We begin our profession of faith by saying: "I believe" or "We believe". Before expounding the Church's faith, as confessed in the Creed, celebrated in the liturgy and lived in observance of God's commandments and in prayer, we must first ask what "to believe" means. Faith is man's response to God, who reveals himself and gives himself to man, at the same time bringing man a superabundant light as he searches for the ultimate meaning of his life. Thus we shall consider first that search (Chapter One), then the divine Revelation by which God comes to meet man (Chapter Two), and finally the response of faith (Chapter Three).
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. Only in God will he find the truth and happiness he never stops searching for:
28 In many ways, throughout history down to the present day, men have given expression to their quest for God in their religious beliefs and behavior: in their prayers, sacrifices, rituals, meditations, and so forth. These forms of religious expression, despite the ambiguities they often bring with them, are so universal that one may well call man a religious being:
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.
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.
33 The human person: with his openness to truth and beauty, his sense of moral goodness, his freedom and the voice of his conscience, with his longings for the infinite and for happiness, man questions himself about God's existence. In all this he discerns signs of his spiritual soul. The soul, the "seed of eternity we bear in ourselves, irreducible to the merely material",9 can have its origin only in God.
34 The world, and man, attest that they contain within themselves neither their first principle nor their final end, but rather that they participate in Being itself, which alone is without origin or end. Thus, in different ways, man can come to know that there exists a reality which is the first cause and final end of all things, a reality "that everyone calls God".10
35 Man's faculties make him capable of coming to a knowledge of the existence of a personal God. But for man to be able to enter into real intimacy with him, God willed both to reveal himself to man and to give him the grace of being able to welcome this revelation in faith. The proofs of God's existence, however, can predispose one to faith and help one to see that faith is not opposed to reason.
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:
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
39 In defending the ability of human reason to know God, the Church is expressing her confidence in the possibility of speaking about him to all men and with all men, and therefore of dialogue with other religions, with philosophy and science, as well as with unbelievers and atheists.
40 Since our knowledge of God is limited, our language about him is equally so. We can name God only by taking creatures as our starting point, and in accordance with our limited human ways of knowing and thinking.
41 All creatures bear a certain resemblance to God, most especially man, created in the image and likeness of God. The manifold perfections of creatures - their truth, their goodness, their beauty all reflect the infinite perfection of God. Consequently we can name God by taking his creatures" perfections as our starting point, "for from the greatness and beauty of created things comes a corresponding perception of their Creator".15
42 God transcends all creatures. We must therefore continually purify our language of everything in it that is limited, image-bound or imperfect, if we are not to confuse our image of God--"the inexpressible, the incomprehensible, the invisible, the ungraspable"--with our human representations.16 Our human words always fall short of the mystery of God.
43 Admittedly, in speaking about God like this, our language is using human modes of expression; nevertheless it really does attain to God himself, though unable to express him in his infinite simplicity. Likewise, we must recall that "between Creator and creature no similitude can be expressed without implying an even greater dissimilitude";17 and that "concerning God, we cannot grasp what he is, but only what he is not, and how other beings stand in relation to him."18
44 Man is by nature and vocation a religious being. Coming from God, going toward God, man lives a fully human life only if he freely lives by his bond with God.
45 Man is made to live in communion with God in whom he finds happiness: When I am completely united to you, there will be no more sorrow or trials; entirely full of you, my life will be complete (St. Augustine, Conf. 10, 28, 39: PL 32, 795}.
49 Without the Creator, the creature vanishes (GS 36). This is the reason why believers know that the love of Christ urges them to bring the light of the living God to those who do not know him or who reject him.
1 Vatican Council II, GS 19 § 1.