I will analyse Descartes’ role in the „theological turn“ of French phenomenology. Although in Husserl’s phenomenology the Cartesian cogito was the central element, in the phenomenologists of the „theological turn“ (Janicaud) it was exchanged for the idea of the infinite. I examine why Marion and Lévinas are interested in the Cartesian idea of the infinite. In the phenomenology of Marion this idea is interpreted as a „conceptual icon“ and a „saturated phenomenon“ ,in the phenomenology of Lévinas this idea represents the structure that provides the possibility of the phenomenological description of transcendence. In order to see if Marion and Lévinas turn back to the onto-theological tradition of the metaphysics, like Janicaud affirms, we have to see how Descartes describes 31 the idea of infinite and how Marion and Lévinas interpret it.