This passage is often used to point to general revelation, the idea that there are aspects of creation which point to God’s nature, at least existence:
For the wrath of God is revealed from heaven against all ungodliness and wickedness of those who by their wickedness suppress the truth. For what can be known about God is plain to them, because God has shown it to them. Ever since the creation of the world his eternal power and divine nature, invisible though they are, have been understood and seen through the things he has made. So they are without excuse; for though they knew God, they did not honor him as God or give thanks to him, but they became futile in their thinking, and their senseless minds were darkened. Claiming to be wise, they became fools; and they exchanged the glory of the immortal God for images resembling a mortal human being or birds or four-footed animals or reptiles.
(Rom 1:18-23, NRSV).
Firstly, this needs to be read in context. Paul was a major figure involved in Gentile inclusion in early Christianity. Contemporary Jews would boast of their righteousness through the law that God gave them and look down on the unrighteous, unclean Gentiles. If some people could come to accept that Gentiles were to be included in the new movement, the next biggest difficulty was being convinced that Gentiles did not need to abide by the Torah. Here Paul speaks of the unrighteousness of the Gentiles, a theme his contemporaries would be familiar with. But then, surprisingly, he goes on to speak of the unrighteousness of the Jews, “You that boast in the law, do you dishonor God by breaking the law? For, as it is written, ‘The name of God is blasphemed among the Gentiles because of you'” (2:23-24), moving onto the universality of sin in chapter 3.
Interestingly, even though Paul makes these statements, he says quite the opposite regarding the gospel: “But how are they to call on one in whom they have not believed? And how are they to believe in one of whom they have never heard? And how are they to hear without someone to proclaim him?… So faith comes from what is heard, and what is heard comes through the word of Christ” (10:14, 17). Additionally, I wonder if Paul’s critique is not merely noetic, but ethical. He is concerned that the Gentiles “suppress the truth” (v.18) and exchange “the truth about God for a lie” (v.25). But perhaps he is more concerned with the life of vices to which he connects it: “They were filled with every kind of wickedness, evil, covetousness, malice. Full of envy, murder, strife, deceit, craftiness, they are gossips, slanderers, God-haters, insolent, haughty, boastful, inventors of evil, rebellious toward parents, foolish, faithless, heartless, ruthless” (vv.29-31). It is not so much denial in itself but denial so that people can cut themselves off from their creator, both objectifying and deifying features of creation in accordance with their desires.
In any case, contemporary religious/secular pluralism should at least hold some interpretative sway for this passage! It remains unfortunate that Christians have used this passage to condemn those who have legitimate doubts about God’s existence or a completely different understanding of God altogether. Perhaps more worrying is its application to non-Christians who may very well be more “ethical” than the Christians condemning them! How do you understand this passage hermeneutically?