The study aims to reconstruct Fabro's reflection on the existential dimension of the natural desire for God starting from some of his writings, mainly The Prayer in Modern Thought. After briefly recalling its metaphysical foundation, attention will be paid to the existential dynamics of the natural desire for God, of which freedom will first be a determining factor. This dynamic, in fact, is seen by Fabro as the area of the cognitive implementation, which is considered, in turn, in correspondence with the role of religiosity and, within it, precisely of freedom, as a manifestation of the person. Prayer will therefore emerge as an act of religiosity and apex of freedom, and, as such, a place for the dynamic synthesis of consciousness in the convergence of the intellect and the will for the choice of the Absolute. Finally, it will be seen how prayer, understood in this way, manages to consolidate in ethos that same desire for truth that specifies the natural desire of God, and is therefore decisive, even beyond atheism itself, for its implementation.