JUDAISM — and Galatians 1:13-14 is one of the word's EARLIEST appearances anywhere. It was coined in the Maccabean literature (2 Maccabees 2:21; 8:1; 14:38) to name the fierce loyalty to the ancestral law that resisted forced Greek assimilation, so it carries a militant edge — not 'the Jewish religion' as a neutral label but ZEALOTRY FOR THE TRADITION. Paul uses it of his OWN former life as the thing he excelled at and then left, which is the point of telling the story to the Galatians: their agitators are selling exactly the mindset he once out-did everyone at. The natural antonym in the same 2 Maccabees is hellēnismos, 'Greek ways'. → first discussed at Galatians 1:13