Youcat commented through CCC. Question n. 4 – Part I.

YOUCAT Question n. 4 - Part I. Can we know the existence of God by our reason?

(Youcat answer) Yes. Human reason can know God with certainty.   

A deepening through CCC

(CCC 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.    

Reflecting and meditating 

(Youcat comment) The world cannot have its origin and its destination within itself. In everything that exists, there is more than we see. The order, the beauty, and the development of the world point beyond themselves toward God. Every man is receptive to what is true, good, and beautiful. He hears within himself the voice of conscience, which urges him to what is good and warns him against what is evil. Anyone who follows this path reasonably finds God.

(CCC Comment)

(CCC 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. (CCC 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).  

(This question: Can we know the existence of God by our reason? is continued)