This article provides an elaborate defense of the thesis that we have no reason to think that sin has any direct effects upon our moral cognition. After a few methodological comments and conceptual distinctions, the author treats certain biblical passages on humans’ evil hearts, the function of the tree of the knowledge of good and evil in Genesis 2 and 3, Paul’s comments on the moral situation of the Gentiles in Romans 2, and Paul’s ideas on the Gentiles’ futility of mind as found in Ephesians 4. The most that can be concluded from these passages is that sin has not damaged human moral cognitive faculties to such an extent that they function insufficiently to hold people morally responsible. The author also argues that it is a consequence of sin that humans have knowledge by acquaintance of sin, and that it is only by divine revelation that humans recognize certain morally reprehensible acts, beliefs, and emotions as sinful. Finally, it is briefly argued that we have good reason to think that sin has certain indirect effects upon our moral cognition.