I was recently asked by a friend of mine to give an interpretation of Romans 1:16. I decided to write it out on here, hopefully to elicit comment and critique. So, here I go.
For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek. Romans 1:16 (KJV)
What does Paul mean here by saying that the gospel goes to the Jew first and also to the Greek? I believe the interpretation is based on the way in which you view the Greek word πρῶτον, translated first. The word carries meaning either in reference to importance and priority, or to chronology. You can quickly see the way in which that interpretation changes the entire text. Either the Apostle is saying that evangelizing Jews is to be of first importance because the gospel is especially to the Jews, or he is saying that the gospel has gone to the Jews first in chronology, in history.
Charles Hodge, the Reformed theologian, points out that,
“To render πρῶτον (first), here especially, would make the apostle teach that the gospel was peculiarly adapted to the Jews, or specially designed for them. But he frequently asserts that this is not the case, Rom. 3:9, Rom. 3:22, Rom. 3:29; Rom. 10:12. πρῶτον, therefore, must have reference to time, ‘To the Jew in the first instance, and then to the Greek.’” 
The interpretation presented by Hodge is the one which has been traditionally held by the Reformed. More recently in terms of Church History, however, the dispensationalist interpretation has arisen. Dispensationalists have a tendency to interpret this passage using the other definition of πρῶτον (first). The idea that the gospel is especially made and intended for Jews, over and opposed to Gentiles, fits into the dispensationalist idea that the Church is a parentheses in God’s plan of redemption.  This system is saying that God’s Kingdom is one which is entirely about Israel; in other words, the Church is not part of the Kingdom, and the Kingdom is not here now. You can see, therefore, how the gospel (which, after all, is the good news regarding the Kingdom of Christ) would be considered primarily for Jews (cf. Mat 15:24).
I believe that the gospel went to the Jews first chronologically, and then continued to expand to the Gentiles, and will continue to expand until it encompasses the globe. The spread of the gospel should not be viewed in terms of people groups, and neither should Christ’s Kingdom. This view makes the most sense when God’s dealings with his people are seen in terms of covenant. Calvin understood this when commented on Romans 1:16 in his commentary. He wrote:
“Under the word Greek, he includes all the Gentiles, as it is evident from the comparison that is made; for the two clauses comprehend all mankind. And it is probable that he chose especially this nation to designate other nations, because, in the first place, it was admitted, next to the Jews, into a participation of the gospel covenant; and, secondly, because the Greeks, on account of their vicinity, and the celebrity of their language, were more known to the Jews. It is then a mode of speaking, a part being taken for the whole, by which he connects the Gentiles universally with the Jews, as participators of the gospel: nor does he thrust the Jews from their own eminence and dignity, since they were the first partakers of God’s promise and calling. He then reserves for them their prerogative; but he immediately joins the Gentiles, though in the second place, as being partakers with them.” 
God deals with his people in terms of covenant—the “gospel covenant” as Calvin calls it. Then, looking at the Scripture chronologically, this passage makes total sense. God sent his gospel covenant to the Jews first, under the old administration of the covenant. Under the new administration through Christ, however, union and communion with Christ spread to all nations (cf. Mat. 28:18-20). This progression of the covenant people is what Paul is talking about in Ephesians 2:11-13, when he wrote:
“Wherefore remember, that ye being in time past Gentiles in the flesh, who are called Uncircumcision by that which is called the Circumcision in the flesh made by hands; That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world: But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ.” (KJV)
Did you catch how the Gentiles were once without Christ, and how being without Christ is referred to both as being “aliens from the commonwealth of Israel” and “strangers from the covenants of promise”? You see, union with Christ cannot be separated from union with his people, or his promises (cf. Eph. 5:25-27, 2 Cor. 1:20-21). In this text then, as well as in Romans 1:16, Paul is talking about the chronological progression of God’s gospel covenant. It went first to the Jews through Abraham, and now it is extended to all the nations through Abraham’s Seed (cf. Gen. 12:1-4, Gal. 3:27). The Church is not a parentheses in God’s plan, while his promises remain unfulfilled. The exact opposite is the case. The Church is the fulfillment of God’s covenant with Abraham—and that gospel covenant will spread to the nations.
- Charles Hodge, Commentary on the Epistle to the Romans. cf. Romans 1:16↵
- Taken from The Millennial Reign by Philip Edgcumbe Hughes, in chapter 2, “[…]the period of the church was inaugurated as a “parenthesis” in the divinely revealed sequence of events, but a period which, as we have indicated, is outside the scope of biblical prophecy and to which Christ’s kingdom teaching has no application[…]” This quote was taken from an article on dispensationalism put together by Ed. F. Sanders, entitled, “What is Dispensationalism?” ↵
- Calvin, John. Commentary on Romans. cf. Romans 1:16↵