In this study, both Tillich`s nothingness and that of Barth are investigated, especially in their doctrines of God, Christologies, anthropologies, and understandings of the problem of evil, which will lead to a better understanding of their existential analyses of being and non-being and their implications with their trinitarian God. To accomplish this task, a comparative study is engaged by examining two theologians` understandings of nothingness: Paul Tillich and Karl Barth. The differences and similarities in their understandings of nothingness will be examined. This study begins with the problems and issues related to the theme of nothingness. It will deals with Paul Tillich`s idea of nothingness. Tillich`s existential and theological understanding of non-being will be probed. Then Barth`s idea of nothingness will be dealt with. In so ding, his biblical and evangelical idea of nothingness will be examined. Moreover, ㅁ theological dialogue between Tillich and Barth will be presented by comparing their ideas that are related to the theme of nothingness such as the doctrine of God, Christology, anthropology, and the problem of evil. This study focuses on the development of their ideas, but particularly as they relate to Hegel. In so doing, it will be demonstrated that Hegel serves as the foundation of the thinking of both. Yet, Tillich serves as the bridge between Hegel and Barth. Both Tillich and Barth are the same in claiming that being is threatened by nothingness. For both, there is enmity and confrontation between being and non-being. However, Tiliich`s argument that God is the absolute non-being is totally different from that of Barth because, for Barth, nothingness is the enemy of God. For Tillich, God produces the absolute threat of non-being, which produces “naked anxiety.” If God is the absolute non-being, it is clear that there is a profound relationship between God and the threat of non-being. That God produces the absolute threat of non-being indicates that God is the solution to the problem related to non-being, that is human finitude. Here, one can say that Tillich`s understanding of non-being is very inclusive in the sense that the absolute threat of non-being is originated from God. This may mean that God is the source of evil. If so, Tillich`s theology is beyond the dualism of good and evil, being and non-being. Both good and evil are included and transcended in Tillich`s God as being-itself. On the contrary, for Barth, nothingness is God`s enemy. The attack of nothingness upon God takes place within God`s good creation. That is to say, the attack of nothingness should be understood in the context of human sin and the fall. The creature has no power to resist the threat of nothingness, so that it surrenders to nothingness. Accordingly, the human being is fallen by rebelling against the grace of God. In this sense, nothingness is the adversary of God and the creature. Barth holds that “the controversy with nothingness, its conquest, removal and abolition, are primarily and properly God`s own affair.” Since God knows and controls nothingness, He can overcome and conquer it. Therefore, God is the Master of nothingness. Barth`s theology falls under the influence of dualism in the sense that nothingness was passed over and negated by God when God created the world. Since Barth`s dialectical theology is to defend the God of justice and his theodicy, he cannot avoid expressing the dualistic characteristic of good and evil. Barth holds that evil is not autonomous. It is not a self-generated being which exists outside of and apart from God`s will. At the same time, it is absolutely no creature of God and no part of his plan. However, he tries to overcome dualism by including evil under God`s permissive will and by not permitting it to have its own autonomous status. That is, Barth wishes to contain evil under God`s absolute rule only in the form of the excluded reality that is apart from God`s positive will.