Perish: This common New Testament word describes the final outcome of the wicked after judgment (see also 9:22; 14:15; 1 Corinthians 1:18; 15:18; 2 Corinthians 2:15; 4:3; Philippians 1:28; 3:19; 2 Thessalonians 2:10; 1 Timothy 6:9). It refers to complete ruin and loss under God’s judgment.
all … under the law: The Jews received the law of Moses, while the Gentiles (non-Jewish people) never had God’s written law. In the New Testament period, Jews saw having the law as a mark of God's favor towards them and even as a guarantee of salvation.