"Bats in the belfry" is a phrase used to describe someone who is considered to be crazy or mentally unstable. The opposite of this phrase would be someone who is level-headed, calm, and rational. Some antonyms for "bats in the belfry" could be "sane," "sound-minded," "reasonable," or "sensible." These words represent a more balanced and collected state of mind, something that is considered normal and desirable in society. It is important to recognize that mental health is a serious issue that should not be taken lightly or mocked. We should strive to embrace and support those who struggle with mental health issues, instead of using derogatory language to describe them.