giving vengeance to those who don't know God, and to those who don't obey the Gospel of our Lord Jesus,
Paul likely has it in his mind that some of the Gentiles have refused the knowledge of God and shown their hatred toward His children (see Romans 1:28-32). It is not, however, likely that he limited the first classification to only Gentiles and the second to only Jews. Both Jew and Gentile could easily be guilty of either of these sins. If a Jew does not know God, he will be lost; and if a Gentile "obeys not the gospel," he, too, will be lost. Thus, the two groups should not be considered as mutually exclusive. I have no problem in understanding that the two classifications refer primarily to Gentiles and Jews, but I have major problems in limiting the first classification to Gentiles only and the second to Jews only.