Paul uses this question to add introduce the next thing he wants to say. If your language uses a different way to introduce new topics, you can use it here. Here the words "stumble" and "fall" are metaphors for sinning and having God reject the sinner. Alternate translation: "Has God rejected them forever because they sinned?" (See: [[rc://en/ta/man/translate/figs-rquestion]])
"That is not possible!" or "Certainly not!" This expression strongly denies that this could happen. You may have a similar expression in your language that you could use here. See how you translated this in [Romans 9:14](../09/14.md).