Which is not another (o ouk estin allo). It is no "gospel" (good news) at all, but a yoke of bondage to the law and the abolition of grace. There is but one gospel and that is of grace, not works. The relative o (which) refers to eteron euaggelion (a different gospel) "taken as a single term and designating the erroneous teachings of the Judaizers" (Burton). Only (ei mh). Literally, "except," that is, "Except in this sense," "in that it is an attempt to pervert the one true gospel" (Lightfoot). Who disturb you (oi tarassonte). The disturbers. This very verb tarassw is used in Acts 17:8 of the Jews in Thessalonica who "disturbed" the politarchs and the people about Paul. Would pervert (qelonte metastrepsai). "Wish to turn about," change completely as in Acts 2:20 ; James 4:9 . The very existence of the gospel of Christ was at stake.