When something is beyond belief or difficult to comprehend, the term "passing belief" comes to mind. There are several synonyms that one can use to express the same sentiment. One possible alternative is "incredible," which means something that is not believable or hard to imagine. Another word that can be used is "unimaginable," which describes something that is too difficult to conceive or comprehend. "Unfathomable" is another term that is synonymous with "passing belief," as it refers to something that is difficult or impossible to understand or explain. Other synonyms for "passing belief" include "mind-boggling," "astonishing," and "inconceivable." Overall, these words can be used interchangeably to convey the same sense of disbelief and amazement.