The author deals with three conencted questions: What is the relation between historical theology and systematic theology? What is the specific scientific character of systematic theology? Does systematic theology need philosophy ot prove her scientific character? After a short review of the previous history of these question (considering Kant, Schleiermachter, Bultmann), the author interprets Heidegger's lecture 'Phanomenologie und Theologie' from 1927/29. According to Heidegger, theology needs philosophy for scientifically proving the ontological background which the conceptions of existence presuppose. But the ontological priority of philosophical analysis is problematic for the purpose of theology. While fundamental ontology in the sense of Heidegger supposes that man is on his own, theology demands a fundamental ontology of communication with God. Nevertheless, systematic theology needs such a discussion as possiility to substantiate her specific scientific model.
