“Paul clearly does believe that when humans look at creation they are aware, at some level, of the power and divinity of the creator.” N. T. Wright, “Romans,” 432.
Although it is tempting to find some kind of Stoicism in Paul’s thought here, he is clearly consistent with Second Temple Judaism. Wisdom 13:1-5 has a similar argument from creation:
Wisdom of Solomon 13:1–5 (NRSV) For all people who were ignorant of God were foolish by nature; and they were unable from the good things that are seen to know the one who exists, nor did they recognize the artisan while paying heed to his works; 2 but they supposed that either fire or wind or swift air, or the circle of the stars, or turbulent water, or the luminaries of heaven were the gods that rule the world. 3 If through delight in the beauty of these things people assumed them to be gods, let them know how much better than these is their Lord, for the author of beauty created them. 4 And if people were amazed at their power and working, let them perceive from them how much more powerful is the one who formed them. 5 For from the greatness and beauty of created things comes a corresponding perception of their Creator.
Neither Paul nor Wisdom of Solomon advocate a “natural theology” in the sense that individuals can obtain salvation only through observation of nature (Schreiner, Romans, 86-7). But as James Dunn says, “it is scarcely possible that Paul did not intend his audience to think in terms of some kind of rational perception of the fuller reality in and behind the created cosmos” (Dunn, Romans 1-8, 58). Both Romans and Wisdom say a person is held responsible for their response to the revelation of a creator from “what has been made.”
A god that has “eternal power” is common to both Jewish and Greek philosophy. The adjective ἀΐδιος is used often in Philo to describe God (“being durable, eternal, and unchangeable” (Alleg. Interp. III 101).
Divine nature (θειότης) also is a word common to Jewish or Greek philosophy. For example, the word is used to describe Artemis, “who made Ephesus famous διὰ τῆς ἰδίας θειότητος, i.e. through manifestations of her power” (SIG 867, 31 ln. 35; BDAG).
Since this revelation is clear and understood, people are without excuse. Although the truth is out there, people “suppress the truth by their wickedness” (1:18), they prevent the truth from having any effect on the way they think. This is a willful disregard for evidence which does not fit into the system of this world’s way of thinking. “Not having an excuse” (ἀναπολόγητος, here and in in 2:1) is used when someone cannot defend themselves against an accusation, so (Plutarch, Brutus 46.2).
Does God’s revelation in creation provide enough knowledge of God to justly punish those who reject it? Although this may have been an adequate argument in the first century, does Paul’s assertion that God has “clearly revealed himself” work as part of a Christian apologetic today?