“…men…suppress the truth unrighteousness, because what may be known of God is manifest in them, for God has shown it to them. For since the creation of the world His invisible attributes are clearly seen, being understood by the things that are made, even His eternal power and Godhead, so that they are without excuse.” Romans 1:18-20.
“The heavens declare the glory of God;
and the firmament shows His handiwork.…There is no speech nor language
where their voice is not heard.” Psalm 19:1-3.
The Catechism affirms that man, even in his fallen state, has the capacity (albeit limited) to know God according to the “natural light of reason”, it is basically referring to to the truth expressed in these two passages from Scripture.
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.. This is because men “suppress the truth in unrighteousness.
Amen.
