Doubt and faith are inseparable from religion or religious belief since they affect how a person and a particular religion relate to God, read scriptures, and develop an epistemic system. This is a comparative study on religion which explores the epistemic nature of faith and doubt in the major religions of Christianity, Islam, Hinduism, and Buddhism. Faith is usually considered as a key to the truths in divinity, in which Abrahamic religions emphasize trust in revelation while Eastern religions treat faith as a subset of a larger pursuit towards enlightenment or self-realization. On the other hand, doubt is understood both as an undermining factor of faith and as a potential to receive a more thorough comprehension of other ideas. While Christianity and Islam predominantly view doubt as a problem to resolve, Hinduism and Buddhism welcome questioning as a fundamental part of spiritual exploration. This study examines the complex relationship between faith and doubt and reveals that rather than being antipodes, they tend to act as two sides of the same coin of religion. This analysis emphasizes the variety of theories and beliefs, showing that religious faith is not simply passive acceptance, but rather a dialectical approach involving endless inquiry, contemplation, and development. Faith and doubt clearly coexist within religious traditions, serving us with an epistemic foundation as well as motivating intellectual and spiritual advancement. Some traditions grapple with doubt while others work through it as an incentive to cultivate understanding. While faith can be perceived as blind trust, there exists another view where faith is regarded as a tool towards more profound understanding. The assertion of faith and doubt brings into question different aspects of religion, resulting in astonishing findings where intense declarations and skepticism are not mutually exclusive, but exist intricately intertwined, shaped in a vivid discourse.