Paul’s use of the OT in Romans is thorough and intentional. It is, after all, for instruction [Rom 15.4]. I was confused when I noticed the frequency of his OT quotations through Romans:
- chs 1-4 [about 15]
- chs 5-8 [only 1]
- chs 9-11 [about 25]
- chs 12-16 [about 15]
The whole epistle flows, but there are definitive indicators [thematic, grammatical, syntactical, theological] that prove that the above chapter divisions are good to keep in mind. Why then does Paul appear to depend so heavily on the OT in most of his argument, but not so much in chapters 5-8? Don’t get me wrong, his thinking is Jewish through and through. But still, why does he not lean upon the text itself in chapters 5-8 as much as he does throughout the rest of the epistle?
The New Covenant people of God live by different redemptive realities than the Old Covenant people of God did. Messiah has come! So, for those under the New Covenant, God put His “law within them and on their heart” [Jer 31.33]. This is of course in contrast to the law being written on stone. God likewise says that He will give His people under the New Covenant a new heart and He will put His Spirit within them [Ezk 36.26-27]. The boundary God set in the OT was the Law. But in the NT, the Spirit is the guide. Perhaps the reason Paul does not quote the OT in Romans 5-8 is because he is expressing a new way to live as one who belongs to God.
You can call this having your mind set on the Spirit [8.5-6]. You can call this presenting your members to righteousness [6.13, 19]. You can call this counting yourself as dead to sin [6.11]. You can call this serving in newness of Spirit and not in oldness of letter [7.6]. You can call this sanctification [6.19, 22]. Whatever this new way of life may be called, Paul cannot look directly to the OT for an explanation of it. Maybe, just maybe, this is why OT quotes are tough to find in Rom 5-8. But if not, I’m not surprised. Just thinkin.