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

Take notice: I, Paul, tell you that if you let yourselves be circumcised, Christ will be of no value to you at all.

For I testify again to every man that is circumcised, that he is a debtor to do the whole law.

Again I testify to every man who gets himself circumcised that he is obligated to obey the whole law.

Christ is become of no effect unto you, whosoever of you are justified by the law; ye are fallen from grace.

You who are trying to be justified by the law have been severed from Christ; you have fallen away from grace.