The essay discusses the main elements of Karl Rahner’s concept of relationship between philosophy and theology. It turns out that Rahner’s thinking in this area of investigation depends on and is submitted to his theology to an enormous extent. The main theological criterion which Rahner puts before philosophy is an acceptance and philosophical openness towards the event of the Incarnation. He places the problem of the relationship between philosophy and theology inside his own theology of nature and grace (in their mutual relationship) from the perspective of the Incarnation. He incorporates both fields of knowledge into fundamental, and at the same time, much broader interpretative pattern offered by the Catholic charitology with its idea of the nature. Rahner’s option, presented here, is heavy with merithorical and methodological consequences. Clear and concrete conditions which theology puts before philosophy as a prerequisite for a potential cooperation does not necessarily infringe the autonomy of the latter. In fact, Rahner recognizes huge importance of theology for philosophy; the former makes the questions posed by the latter all the more far reaching and relevant. In Rahner’s vision theology helps to maintain the questions posed by philosophy opened, and answers them in such a manner that makes them radically and constantly opened. It does service to theology as well. The bound between philosophy and theology, founded on the Incarnation and grace, is thus organically mutual.