Berikut ini adalah kutipan langsung dari: Douglas J. Moo, Romans; The NIV Application Commentary (Grand Rapids, Michigan: Zondervan, 2000), 59-60.
Verse 18 comes to the reader as quite a surprise. Paul has just announced his theme for the letter: the gospel as God’s saving power, revealing his righteousness to all who believe. But instead of the exposition of these wonderful truths, we get dire news about God’s wrath against sin. Indeed, it is not until fully two chapters later, in 3:21, that Paul finally picks up on the themes he broached in 1:16-17. Why is this? Apparently Paul thinks it necessary to make clear just why the revelation of God’s righteousness in the gospel is necessary. Only by fully understanding the “bad news” can we appreciate the “good news”. Thus, Paul goes to some lengths to detail for us the nature and dimension of the human predicament (1:18-3:20).
His argument moves in several clearly marked stages. Heading the entire section is the announcement of God’s wrath against sin (1:18-20). But almost as important in this announcement is his insistence that God’s wrath is earned: Human beings have suppressed God’s truth. Paul goes on to show how all people, Gentiles (1:21-32) and Jews (2:1-29) alike, have rejected God’s truth and brought justly on themselves God’s wrath. In 3:1-8 Paul moves away from the main story line to qualify what he says in chapter 2 about the privileges of the Jews. Then, in 3:9-20, he brings the discussion to a close with a final indictment of humanity.
The particular section we are now dealing with divides into three basic parts: God’s wrath against sin and its basis (1:18-20), people’s suppression of truth and its consequences (1:21-31), and a concluding indictment (1:32).
God’s Wrath against Sin and Its Basis (1:18-20)
Verse 18 appears at first sight to be closely related to verses 16-17. A gar (“for”) connects verse 18 with what comes before it, and both verses 17 and 18 use the verb “reveal”. On this basis a few interpreters have concluded that the revelation of God’s righteousness (v.17) and the revelation of his wrath (v.18) are both parts of the gospel (v.16). But the negative note of God’s wrath does not fit Paul’s consistently positive use of the word “gospel”. Probably, then, the “for” that begins this verse introduces all of the section that follows: It is necessary for God to reveal his righteousness in the gospel because God has also found it necessary to reveal his wrath against sin.
Some modern translations use the term “anger” instead of “wrath” for the Greek word used here (orge). But “wrath” while a bit old-fashioned, preserves the more ovjectives sense the Greek word has when applied to God. God’s reaction to sin is not the “anger” of an emotional person; it is the necessary reaction of a holy God to sin. The Old Testament regularly speaks of God’s inflicting wrath on people, both in the course of history (e.g. Ex. 32:10-12; Num. 11:1; Jer. 21:3-7) and, especially, at the end of history. Paul usually also depicts God’s wrath as coming at the Parousia (see, e.g., Rm. 2:5,8; 5:9; Col. 3:6; 1Tes. 1:10). Because of this, some interpreters think that the verb “is being revealed” is a futuristic present, meaning “will be revealed”. But Paul is probably referring broadly to the sentence of condemnation that all people stand under – a sentence that God sometimes inflicts in the events of history but will carry out with finality at the end of history.
Especially important for Paul is his insistence that God’s wrath falls on people who “suppress the truth”. One can only suppress something of which one has knowledge. As a result, Paul goes on in verses 19-20 to show that this word is entirely appropriate to use in describing people’s relationship to God’s truth. Human beings do have knowledge aboud God. He has revealed it to them(v.19b), manifesting some of his divine qualities in the world he has created (v.20). Moreover, these qualities “have been clearly seen” by people.
Paul here establishes the truth of what we sometimes call “natural revelation”: God discloses something of his existence and nature to all people in the created natural world (for more on this, see the Contemporary Significance section). Yet the end of verse 20 already anticipates the negative direction that Paul’s argument about natural revelation will take: “so that men are without excuse.” Rather than bringing people into relationship with God, natural revelation makes them guilty. Why this is so and how it has happened will be the focus of the next section (1:21-31).
 See esp. Karl Barth, A Shorter Commentary on Romans (Richmond: john Knox, 1959), 42-43; Cranfield, The Epistle to the Romans, 106-108.
 See, e.g., Sanday and Headlam, The Epistle to the Romans, 41.