Link: 3. Canons of Dort

Article 4: The Inadequacy of the Light of Nature

To be sure, there is left in man after the fall some light of nature, whereby he retains some notions about God, (1.) about natural things, and about the difference between what is honorable and shameful, and shows some regard for virtue and outward order. But so far is he from arriving at the saving knowledge of God and true conversion through this light of nature that he does not even use it properly in natural and civil matters. Rather, whatever this light may be, man wholly pollutes it in various ways and suppresses it by his wickedness. In doing so, he renders himself without excuse before God. (2.)

Romans 1.19-20 (ESV):
For what can be known about God is plain to them, because God has shown it to them.
For his invisible attributes, namely, his eternal power and divine nature,
have been clearly perceived, ever since the creation of the world,
in the things that have been made. So they are without excuse.
Romans 2.14-15 (ESV):
For when Gentiles, who do not have the law, by nature do what the law requires,
they are a law to themselves, even though they do not have the law.
They show that the work of the law is written on their hearts,
while their conscience also bears witness,
and their conflicting thoughts accuse or even excuse them.

Romans 1.18, 20 (ESV):
For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who by their unrighteousness suppress the truth...v.20,For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse.