yet who know that a man is not justified by works of the law but through faith in Jesus Christ, even we have believed in Christ Jesus, so that we may be justified by faith in Christ, and not by works of the law, because by works of the law will no flesh be justified.

Is the law then opposed to the promises of God? Certainly not! For if a law had been given which could impart life, then righteousness would indeed have come by the law.

Behold I, Paul, say to you that if you receive circumcision, Christ will be of no benefit to you.

For, being ignorant of the righteousness that comes from God, and seeking to establish their own, they did not submit to God's righteousness.

And if it is by grace, then it is no longer on the basis of works; otherwise, grace would no longer be grace.

Now if perfection could have been through the Levitical priesthood (for on the basis of it the people received the Law), what further need was there for another priest to arise according to the order of Melchizedek, and not one designated according to the order of Aaron?

Christ

by which also you are saved, if you hold fast the word which I preached to you, unless you believed in vain.

General references

For if I rebuild what I destroyed, I prove myself a transgressor.