Paul is using irony and a rhetorical question to say that the Galatians are acting as though someone has put a spell on them. He does not really believe that someone has put a spell on them. AT: "You behave as if someone has put a spell on you!" (See: [[rc://en/ta/man/translate/figs-irony]] and [[rc://en/ta/man/translate/figs-rquestion]])
Paul speaks of his clear teaching of Jesus being crucified as if he had put on public display a picture of Jesus being crucified. And he speaks of the Galatians having heard his teaching as if they had seen the picture. AT: "You yourselves heard the clear teaching about Jesus being crucified" (See: [[rc://en/ta/man/translate/figs-metaphor]])
This continues the irony from verse 1. Paul knows the answers to the rhetorical questions he is about to ask. (See: [[rc://en/ta/man/translate/figs-irony]])
Translate this rhetorical question as a question if you can, because the reader will be expecting a question here. Also, be sure that the reader knows that the answer to the question is "by believing what you heard," not "by doing what the law says." AT: "You received the Spirit, not by doing what the law says, but by believing what you heard." (See: [[rc://en/ta/man/translate/figs-rquestion]])
This rhetorical question shows that Paul is surprised and even angry that the Galatians are foolish. AT: "You are very foolish!" (See: [[rc://en/ta/man/translate/figs-rquestion]])