Romans 7:6

But now we have been discharged from the law, having died to that wherein we were held; so that we serve in newness of the spirit, and not in the oldness of the letter.

Now that we have ... shows that Paul was here identifying himself as a former disciple of the law, thus including himself with the Jewish Christians to whom he addressed this appeal. Paul's use of the first person here should be noted.

Newness of the spirit ... oldness of the letter ... These phrases refer to the life "in Christ Jesus" on the one hand, and to life under Moses' law on the other. "Oldness of the letter" is a reference to exactly the same thing that that was signified by the use of "in the flesh" in the preceding verse. Paul's various usage of the same phrase is again apparent in that. In this paragraph, "flesh" means the covenant of flesh, or the law of Moses; in Galatians 2:20, it means alive in the physical body; and in Romans 8:9, it has reference to living after the lusts of the flesh.

Sanday's exegesis on the meaning of this verse is,

The true reading runs thus: "But as it is, we were (we are) delivered from the Law, having died to that wherein we were held. In the act of our baptism which united us to Christ, we obtained a release from our old tyrant, the Law."[5]

The insinuation that "oldness of the letter" has reference to obeying the commandments of Christ, and that "newness of the spirit" means being saved by "faith and nothing but faith" is unfounded, and such a construction of Paul's words is an unjustifiable distortion.