Immanuel Kant said this quote

We have seen, therefore, that I am not allowed even to *assume*, for the sake of the necessary practical use of my reason *God, freedom, immortality*, unless at the same time *I deprive* speculative reason of its pretensions to transcendent insights. Reason, namely, in order to arrive at these, must employ principles which extend only to objects of possible experience, and which, if in spite of this they are applied also to what cannot be an object of experience, actually always change this into an appearance, thus rendering all practical *expansion* of pure reason impossible. Hence I had to suspend *knowledge* in order to make room for *belief*. For the dogmatism of metaphysics without a preceding critique of pure reason, is the source of all that disbelief which opposes morality and which is always very dogmatic. ―from_Critique of Pure Reason_. Preface to the Second Edition. Translated, edited, and with an Introduction by Marcus Weigelt, based on the translation by Max Müller, pp. 25-26