Alexander Gottlieb Baumgarten's ethics had a significant influence on the formation of Kant's ethics. The extent of this influence, however, has not been sufficiently investigated by existing Kant scholarship. Filling this gap, this paper aims to reveal Baumgarten's substantial influence on the formation of Kant's ethics, particularly the complex ways in which Kant's ethics retains the concept of God as crucial for ensuring that his ethics persist under the scrutiny of reason. In a systematic comparison of the ethics of the two philosophers, I argue that Kant alters and yet accommodates several aspects of Baumgarten's ethics in his own version of the system of ethics more thoroughly than has previously been perceived. More specifically, I argue, first, that Kant's rejection of Baumgarten's conception of "duties towards God" and his alternative notion that duties are recognized as if they were divine commands unveil his criticism of Baumgarten's conception of how religion is situated in ethics. Second, I argue that Kant's argument for the extension of pure reason for practical purposes discloses his critical response to Baumgarten's optimistic assumption about the entirety of pure reason.