Galatians 1:7

Galatians 1:7. Which (pseudo-gospel of the heretical teachers) is not another, i.e., no gospel at all, but a perversion and corruption of the one unchangeable gospel. The gospel of Paul teaches that man is justified by grace alone through faith in Jesus Christ; the pseudo-gospel of the Judaizers teaches that man is justified by grace and works through faith in Christ and the circumcision of Moses. The former makes good works the effect, the latter the cause, of justification; and this is thus in fact a relapse into the Jewish standpoint under a Christian name.

Save that there are some troubling you. Only in this sense is it another gospel that it is a perversion of the true gospel of Christ by those well-known troublers of your conscience.