The emergence of Islamist terrorism, which violently peaked in previous years, particularly triggered by September 11th and the destruction of the Twin Towers, reignited the conflict between East and West, the Islamic and Christian worlds. Thus, the oversimplified distinction of the world into good and evil, sacred and profane, pure and impure, resurfaced – a distinction which, in practice, neither ‘explains’ nor, more importantly, addresses the complex reality of the multicultural global community in which we live. This work examines the encounter between Christianity and Islam, the dialogue between the two religions, as well as their comparative perspective. Concurrently, the influences of Judaism, and of a segment of Christians whose traces disappear after the first millennium, on Muhammad and the Quran are explored. The main focus of the study is the comparison between the Holy Bible and the Quran, as well as between other fundamental sources of the two religious traditions, across a variety of topics concerning faith and ethics. Thus, the reader is introduced, in a concise yet scholarly manner, to the genesis and diversity of early Christianity, as well as to the evolution of Islam’s formation, which spread rapidly throughout the Mediterranean basin. This study highlights the significance of Christianity for the religion of Islam, regarding the understanding of both its origin and its nature. This study aims to illuminate this interpenetration and dialectical relationship between the two religions, premised on fruitful dialogue and reciprocal understanding between two worlds called upon, in the post-COVID era, to face new challenges.