本研究企圖藉檢視海德格充滿神祕色彩的「存有」之問，以探討海德格哲學的宗教向度與其根源，嘗試跟中世紀神祕主義的艾克哈特大師（Master Eckhart）的上帝觀作出關聯性的比較。艾克哈特大師將上帝分別跟「存有」（Being）及「虛無」（Nothingness）等同；上帝既是「存有」又是「虛無」，這個看似矛盾的主張表達一個洞見：上帝不能跟任何事物相提並論、不能被實體化或物化。僅有在「去物化」（disembodiment）中，我們才可能經歷到上帝。　　海德格也曾經將「存有」跟「虛無」等同，其對作為「虛無」之「存有」的描述跟艾克哈特對於上帝作為既是「存有」又是「虛無」的陳述不謀而合。顯然海德格只是透過「存有」之迂迴的途徑來趨近其「上帝」。而其──介於「存有」跟「存在物」之──「存有論的差異」其實真正要表達的是：上帝跟其受造物絕對的不同。海德格基本存有論其實是充滿神學的色彩，其對「存有」的神祕化僅能以其神祕的上帝觀才能恰當說明。

This paper attempts to examine Heidegger’s mystical question of Being in order to investigate the religious aspects of Heidegger’s thought, as well as their sources, endeavoring to make a comparison between these and the views on God held by Master Eckhart, a proponent of mysticism in the Middle Ages. Master Eckhart equates God with Being and Nothingness. This seemingly paradoxical proposition that God is both Being and Nothingness in fact expresses an insight, namely, that God cannot be placed on par with anything and cannot be hypostatized or reified. We can only experience God in a state of disembodiment. Heidegger also equated Being and Nothingness before, and his description of Being as Nothingness aligns completely with Eckhart’s assertion that God is both Being and Nothingness. It is evident that Heidegger simply approaches his “God” through the indirect path of Being. In fact, what his ontological difference between Being and beings really expresses is the absolute distinction between God and His creations. Heidegger’s fundamental ontology is really suffused with theological ideas; his mystification of Being can only be made appropriately clear through his mystical vision of God.