knowing that a man is not justified by the works of the law, but by faith in Jesus Christ, even we have believed in Christ Jesus, that we might be justified by faith in Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.

Is the law then contrary to the promises of God? not at all: for if a law had been given, which could have confered life, certainly righteousness would have been by the law.

Behold, I Paul say unto you, that if ye be circumcised, Christ will profit you nothing.

For being ignorant of the righteousness of God, and seeking to establish their own righteousness, they have not submitted themselves to the righteousness which is of God.

And if by grace, it is no more of works: for then grace is no longer grace. But if of works, it is no more grace: for then work is no longer work.

Now if perfection were by the Levitical priesthood, (for under it the people received the law) what farther need was there that another priest should arise after the order of Melchisedec, and not after the order of Aaron?

Christ

By which also ye are saved, if ye retain it as I preached it to you: unless indeed ye have believed in vain.

General references

God forbid. And if I build again the same things which I demolished, I shew myself a transgressor: for I through the law am dead to the law,