A few more things to add to that last post (again from the CCC):

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." 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".

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. 2 # 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.