Establishing a standard of truthfulness is crucial for ensuring access to accurate and reliable knowledge across all domains, particularly in the realm of religious knowledge. The significance of this endeavor arises from the central role religious knowledge plays in shaping beliefs, guiding conduct, and fostering moral values within individuals and societies. This article examines the standards of truthfulness applied to religious propositions, focusing on achieving correspondence between these propositions and authoritative religious texts or observable reality, thereby ensuring alignment with divine objectives. Furthermore, the article explores the relationship between religious knowledge and reason, including self-evident truths, as a foundation for constructing sound propositions. Epistemological theories, such as the correspondence theory, pragmatism, and coherence theory, are critically analyzed in this context. The analysis specifically applies these standards to doctrinal, ethical, and behavioral issues, providing illustrative examples of their interaction with religious texts. The role of both reason and revelation in achieving truthful cognitive propositions is emphasized. A key finding is that the fundamental standard for the truthfulness of doctrinal, ethical, and legal propositions is their correspondence with reality, verifiable through reason using self-evident truths or authentic religious texts. Consequently, doctrinal, ethical, and legal knowledge rests upon a firm foundation that integrates both reason and revelation.