The article provides a detailed and critical analysis of Heidegger’s approach to the concept of eternity, as elaborated on in his texts of 1924–1927. This approach can be described in the light of a threefold outlook, to wit: as a philosophical inadequacy of the theological concept of eternity; as a rejection of the concept of traditional metaphysical eternity, based on Heidegger’s interpretation of the history of philosophy; and as a Project for eternity’s philosophical perception that is compatible with the analysis of original temporality (Being and Time). In his 1924 discourse The Concept of Time, Heidegger strictly separates between the philosophical consideration of the time problem and eternity concept, the latter being, according to him, basically theological in its nature. Such separation is grounded on the argument typical to Heidegger in the 1920s: there is no way for philosophy and theology to be united for a philosopher is irreligious per se. Philosophical inquiry of time, therefore, is valid only when based on time as experienced, and the problem of eternity should be left for theologians. [...]