Yahweh rebukes the priests using an imaginary conversation in which the priests protest that they are doing right and Yahweh tells them what they are doing wrong.
Here the priests are asking a question in order to state that they have not really despised Yahweh. This can be expressed as a statement. Alternate translation: "We have not really despised your name." or "Tell us how we have despised your name, because we do not think that we have done so." (See: [[rc://en/ta/man/translate/figs-rquestion]])