Catechism of the Catholic Church
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, imagebound 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}.
46 When he listens to the message of creation and to the voice of conscience, man can arrive at certainty about the existence of God, the cause and the end of everything.
47 The Church teaches that the one true God, our Creator and Lord, can be known with certainty from his works, by the natural light of human reason (cf. Vatican Council I, can. § # 1: DS 3026),
48 We really can name God, starting from the manifold perfections of his creatures, which are likenesses of the infinitely perfect God, even if our limited language cannot exhaust the mystery.
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.
2 Acts 17:26-28.
3 GS 19 § 1.
4 Cf. GS 19-21; Mt 13:22; Gen 3:8-10; Jon 1:3.
5 Ps 105:3.
6 St. Augustine, Conf. I, I, I: PL 32, 659-661.
7 Rom 1:19-20; cf., Acts 14:15, 17; 17:27-28; Wis 13:1-9.
8 St. Augustine, Sermo 241, 2: PL 38, 1134,
9 GS 18 § 1; cf. 14 § 2.
10 St. Thomas Aquinas, S Thess I, 2, 3.
11 Vatican Council I, Dei Filius 2: DS 3004 cf. 3026; Vatican Council II, Dei Verbum 6.
12 Cf. Gen 1:27.
13 Pius XII, Humani generis 561: DS 3875.
14 Pius XII, Humani generis 561: DS 3876; cf. Dei Filius 2: DS 3005; DV 6; St. Thomas Aquinas, S Thess I, I, I.
15 Wis 13:5.
16 Liturgy of St. John Chrysostom, Anaphora.
17 Lateran Council IV: DS 806.
18 St. Thomas Aquinas, SCG 1, 30.
English Translation of the Cathechism of the Catholic Church for the United States of America © 1997, United States Catholic Conference, Inc.