Shiite Vitality Why is Shia Islam in the “Age of the Decline of Religions” Dynamic? To answer this question, this study will briefly refer to its main reasons, such as: -The Religion of Islam. -The Plausible Belief System. -The Holy Quran. -The Prophet Muhammad (s). -The Authentic Transfer of Islam by the Infallible Imams (s). -The Efforts of Muslim Scholars. -The Fidelity of the Individual Muslims. -The Faithful Perception of Being. -The Shiite Sources of Knowledge. -Living under Supervision of a living Imam.