The aim of the study is a critical analysis of Sitarčíková ́s theological and teleological arguments against radical human enhancement. Sitarčíková (2012) argues that it is necessary to protect human nature from (bio)technological interventions since they will lead to the destruction of human nature. Conseqently, humans will be deprived from the possibility to conduct right life and reach the final objective of their existence, which is understanding God. We will also demonstrate that Sitarčíková ́s argument can be transformed into a secular version, which would make it palatable for a secular bioethical discourse. However, since the basis of the argument is a metaphysical concept of human nature, at the end it has to be abandoned.