Roman Catholic bioethics seems to be caught in a paradox. On the one hand it is committed to the natural law tradition and the power of reason to understand the structures of creation and the moral law. On the other hand there is a greater and greater appeal to Scripture and revelation. The tradition maintains that reason is capable of understanding the rational structures of reality and that ethics is properly built on metaphysics. In this way ethics, bioethics, is non-sectarian. However, the tradition also recognizes the effects of Original Sin on the will and intellect and the broad cultural changes that have affected our understanding of metaphysics. The appeal to Revelation is a corrective to many contemporary trends in ethics and bioethics. This article will examine the interplay of reason and revelation in the Church's teaching on sexuality (particularly contraception and in vitro fertilization), suffering, and death. Catholic bioethics is in the end prophetic and ecumenical and not gnostic and non-ecumenical.