This study evaluates the concept of interreligious dialogue and its relation to Islam. It engages in textual analysis and the historical interpretation of the Qur’an and Sunnah. The analysis includes the treatment of early Muslim rulers, especially the second caliph of Islam “Umar,” for the followers of other religions in an attempt to understand the nature of interreligious dialogue in Islam. The research shows how Islam plays a unique role in promoting interreligious dialogue by providing justice, equal rights, and the freedom of religious beliefs and practices of any religion, culture, and civilization as well as accepting all previous prophets as the Prophets of Islam. The study concludes with the strongest emphasis that Islam is a comprehensive religion that advocates harmonious interreligious relationships. It can be taken as a model for mitigating interreligious conflicts and for promoting interreligious harmony and peaceful co-existence in this world of diverse faiths and traditions.