Those people are zealous for you: The Greek word here can mean have a positive meaning, like "eagerness," or a negative meaning, like "jealousy" and "envy."
they want to isolate you from us: The Judaizers (Jewish Christians insisting on following Jewish laws) might have been so eager because they envied the Galatians’ devotion to Paul and instead wanted the Galatians to be devoted to them (compare 2 Corinthians; see also Luke 11:46–52). Another possibility is that the Judaizers wanted the Galatians to depend on them as interpreters of the law of Moses.