Romans is a complex logical argument, and much of the logic is derived from the OT. In a sense this is a research document, with its primary source being the OT. In addition to a great many allusions to the OT, Paul directly quotes it 63 times.  And at least 14 OT books are quoted by Paul (Genesis, Exodus, Leviticus, Deuteronomy, 1 Samuel, 2 Samuel, 1 Kings, Job, Psalms, Proverbs, Ecclesiastes, Isaiah, Jeremiah, Ezekiel, Hosea, Joel, Nahum, Habakkuk, Malachi), with Isaiah and Psalms being the most frequent.

In all the NT, there are approximately 319 quotations from the OT; so Romans accounts for almost 20% of those quotations. There are more quotations in Romans than in any other NT book (Matthew is next with 54, Acts with 40, and Hebrews with 37). In fact, Paul quotes the OT more in Romans than in the remainder of his 12 other letters combined (44x),and he quotes the OT more in Romans than the General Epistles combined (54x). [Interestingly, six of his letters contain no OT quotations: Philippians, Colossians, 1-2 Thessalonians, Titus, and Philemon. Five other letters contain no OT quotations: 1-3 John, Jude, and Revelation.]

It is also interesting to note in what sections Paul uses the OT most heavily in this letter. Here is a breakdown by chapter of the OT quotations in Romans (a complete chart of the exact quotations is available here):

  • Chapter 1 = 1x
  • Chapter 2 = 2x
  • Chapter 3 = 7x
  • Chapter 4 = 6x
  • Chapter 5 = 0x
  • Chapter 6 = 0x
  • Chapter 7 = 1x
  • Chapter 8 = 1x
  • Chapter 9 = 12x
  • Chapter 10 = 12x
  • Chapter 11 = 9x
  • Chapter 12 = 2x
  • Chapter 13 = 2x
  • Chapter 14 = 2x
  • Chapter 15 = 6x
  • Chapter 16 = 0x

So in the section on the relationship between Jews and Gentiles in the body of Christ and eternal plan of God (chs. 9-11), Paul uses more than half of the OT quotations in the book (33x). And in the heart of the book in the section on the sanctifying work of the gospel (chs. 5-8) he uses only two OT quotations.

Further, “more than half of the Pauline examples of [‘it is written’] are found in Romans. It was a valuable asset to be able to say, when dealing with doctrinal truth, it stands written.” [Harrison, 306]

Schreiner relates the use of the OT in this letter to Paul’s purpose of reconciling the Jews and Gentiles in the Roman church:

The conflict between Jewish and Gentile Christians in Rome was rather typical of the kind of debates that occurred as the gospel spread throughout the Greco-Roman world. Paul could not arbitrate the debate simply by declaring his opinion. He needed to summarize the basic content of the gospel he preached, especially as it pertained to issues relating to Jews and Gentiles. It is not surprising, therefore, that the Mosaic law and the place of Israel in salvation history are at the forefront of the discussion in Romans. Paul also needed to explicate his gospel thoroughly because he was the object of constant attacks, especially by other Jewish Christians. If he merely communicated his judgments on the controverted issues without providing a full exposition of his gospel, some would have rejected his advice immediately, knowing that Paul was under suspicion by some in Jerusalem (cf. Acts 21:20-21).…These apprehensions about Paul’s preaching in Rome could perhaps be alleviated if his gospel were thoroughly explained, particularly on issues relating to Jews and Gentiles. He must satisfy both Jewish and Gentile Christians that his stance on the Mosaic law, circumcision, and the place of Israel accords with the OT Scriptures.…Paul’s intention is to show them that his gospel constitutes the true fulfillment of what the OT Scriptures teach about Mosaic law, circumcision, and the role of Israel (and Gentiles) in salvation history. [20-21]