Karl Jasper refers the period from B.C.800 to B.C.200 to Axial Age, an era that set forth the beginning of moral civilization of human beings. During the Axial Age, the idea of monotheism grew in Israel, and later on developed into Judaism, Christianity, and Islam. Nonetheless, since monotheism dealt with the one and only God, it was misinterpreted as if monotheism meant the belief in the “one” god, or the “highest” god out of “multiple” gods. In fact, monotheism sometimes functioned as a reinforcement of exclusiveness and self-centeredness as the one and the only God reflected the image of absolute monarchy. This thesis primarily discusses the Biblical events that led to the creation of monotheism along with the events that took place as monotheism was being created to help readers better understand and apply the term “One(mono) God(theos)” to the society today. Through the close understanding of panentheism, or all-in-God-ism, what kinds of religious aspects monotheism was oriented and what it really meant to propose can be distinctly realized. As God not only exists inside all things but also transcends them, panentheism comprehensively covers up to polytheism (the belief in many gods), pantheism (the belief that everything is god), and even atheism (the disbelief in the existence of god). This thesis analyzes different biblical perspectives along with various historical events so that the term “only God” better suites the modern society and ultimately promotes healthy understanding of God based upon panentheism.