When we hear someone saying that something is "as gospel", it means they consider it to be unquestionably true or reliable. However, there are numerous synonyms for this popular idiom. One can replace "as gospel" with phrases like "as the truth itself", highlighting the unwavering certainty of the information being conveyed. Alternatively, one can use expressions like "beyond reproach", "beyond doubt" or "beyond question" to emphasize the indisputable nature of the statement. "Set in stone" is another perfect substitute, denoting that the information is unchangeable and absolute. These alternatives effectively capture the notion of infallible truth, enabling us to express ourselves with a diverse range of phrases that convey the same sentiment as "as gospel."