Instead of drifting off miles away from 2 Cor 5, how about looking at expression he just used 1 chapter earlier, or 2? That's where he said what kind of minister he was in the new covenant, and continued on.
How is it that with all that time (3 chapters) he NEVER once says: now remember all this is around and beside the land promise, which is God's "other" program in which every rule, ethic, phrase, term has a completely different meaning, because that's OK because God is bi-polar, or schitzophrenic, and wants the Bible to be confusing.
Don't blame the MADist for you having run off to the bookstore when you could have just stuck it out in Scripture; as we are each supposed to.
In 2 Cor. 3, and elsewhere, in his writings, Paul is talking about that aspect or "sufficiency" in Christ promised in Israel's New Testament to Israel that Christ's blood made possible, and that the Spirit of God will enable the Israelite's spirit to walk in one day, but that the Spirit of God was now making the Gentiles' spirit "able" to walk in.
Its the same God; the same Christ; the same Spirit; the same enabling - but - it is neither by Covenant, nor unto the same purpose.
Israel; saved according to God's Covenant with Abraham; will be enabled to keep the Law (the Law is what identifies them as the people of God on the earth in the sight of the nations, Dt. 4:5-8; Rm. 2:17-20; 3:1-3, etc.).
In contrast, those lost Jews and Gentiles saved this side of Israel's temporary fall, and raising up of the Apostle of the Gentiles, are BOTH saved AS GENTILES - by Grace; absent of Covenant, Rm. 3-5; Eph. 2, etc.).
Titus 2:11 For the grace of God that bringeth salvation hath appeared to all men, 2:12 Teaching us that, denying ungodliness and worldly lusts, we should live soberly, righteously, and godly, in this present world; 2:13 Looking for that blessed hope, and the glorious appearing of the great God and our Saviour Jesus Christ; 2:14 Who gave himself for us, that he might redeem us from all iniquity, and purify unto himself a peculiar people, zealous of good works. 2:15 These things speak, and exhort, and rebuke with all authority. Let no man despise thee.
Titus 3:4 But after that the kindness and love of God our Saviour toward man appeared, 3:5 Not by works of righteousness which we have done, but according to his mercy he saved us, by the washing of regeneration, and renewing of the Holy Ghost; 3:6 Which he shed on us abundantly through Jesus Christ our Saviour; 3:7 That being justified by his grace, we should be made heirs according to the hope of eternal life. 3:8 This is a faithful saying, and these things I will that thou affirm constantly, that they which have believed in God might be careful to maintain good works. These things are good and profitable unto men.
In fact, much of the issues described in 2 Cor. 3, are the same enablement issues described, say, in Romans 6-8.
The latter part of 2 Cor. 3 matching issues (concerning Israel's yet future spiritual liberating, described also, in Romans 9-11, and so on).