If they are studied carefully and prayerfully, most scripture texts/passages will quite readily give up their meaning. Others require extra study and prayer. But there is no better interpreter than Scripture itself under the guidance of the Holy Spirit.
The more Romans 6 is prayerfully studied, the clearer it should become that it addresses the life experience of the believer rather than the historical old and new covenants. Even the seminal death and resurrection of Jesus are not emphasized as historical events per se in 6:1–10, but are presented in terms of how they affect the life and behavior of the believer. Romans 6 does not even emphasize Jesus’ historical death and resurrection as the basis for the forgiveness of the believer’s sins, but rather speaks of it as the basis through baptism for the believer’s own personal death to sin and rising to “walk in newness of life” (v. 4). The believer’s baptismal identification with Jesus’ death and resurrection becomes the experiential transition point from living as “slaves of sin” to living as “slaves of righteousness” (vv. 17, 18). The entire chapter is experiential, not historical in nature.
This is the context for verses 11–14 in general and for verse 14’s “you are not under law but under grace” in particular. The context, as well as the specific wording of the entirety of verse 14, readily gives up its meaning as experiential, not historical, in orientation. When Paul writes in verse 14, “You are not under law,” he was not teaching that the law no longer has any application to the New Testament believer; when he writes “you are under grace,” he was teaching that at conversion you died to a life committed to a sinful lifestyle and you rose committed to live a righteous life that will honor Jesus and contribute to the expansion of His kingdom on earth. In other words, your response to the gospel in faith and a commitment to an obedience that comes from faith as God writes His law on your heart marks your transition from an old-covenant experience to a new-covenant experience, from an old-covenant person to a new-covenant believer.
Consider again the implications if verse 14 refers to the historical old and new covenants. Consult the list of contrasts on the inGest chart/slide for verses 11–14. If the left-column characterizations of the “old covenant” all applied to the Sinai covenant, then that covenant would have been designed by God to keep people “alive . . . to sin” and under sin’s “dominion” and “reign,” requiring that they obey its “lusts” and serve “wickedness”! And not until Jesus came in history could any of the benefits of living “under grace” have been experienced by anyone.