In this paper, Imam Sayyid Musa Sadr examines the definition of humanness by offering theories given by Greek peripatetics, determinists, socialists, and materialists. He concludes that God is the primary being capable of defining humanness, and offers ways in which humanness can be achieved as stated in the Holy Qur’an. To further elucidate on this topic, Sadr also explains the effects belief in one God has on a person’s spiritual and mental state. Human beings have an honourable status, are created by the best Creator, and are given the opportunity to be God’s vicegerent on earth. With this, they are given the choice to be God’s righteous servants by enduring life’s adversities as a means to develop in various ways, achieve humanness through Islamic morality, and work together as one united body to gain Allah’s (swt) pleasure in this world and in the afterlife. This paper was delivered by Imam Musa Sadr at the Sixth Annual Conference of Assembly for Islamic Research (Majma‘ al-Buhūth al-Islāmiyyah) in Cairo, held on March 30th 1971. This paper is published in Farsi in Adyān Dar Khedmat-e Insan and has been translated from Farsi into English for the Message of Thaqalayn by Mohammad Reza Farajian.