In the US and elsewhere, creationist groups have challenged the mandatory science curriculum because it introduces the theory of evolution as the true story of biodiversity. This paper disaggregates this challenge in two distinctive levels. On the substantive level, creationists claim that Darwinian evolution is not value-neutral, as most scientists portray it, but it works as a philosophically-loaded theory that amounts to naturalism, which is a comprehensive doctrine that undermines traditional theism. Creationists then contend that its exclusive teaching violates the liberal promise of religious neutrality. To restore metaphysical fairness, they propose to include non-naturalistic theories into the official curriculum as a way of balance. On the epistemic level, creationists criticise liberal institutions--from courts of justice to educational boards and executive officials--that demarcate science in a way in which supernatural hypotheses can never compete for the best factual explanation. Under the guise of a purely methodological naturalism, they argue, liberals are opting for a cognitive filter that is biased against the belief that God intervenes in cosmic history. To restore epistemological fairness, they propose that theories that suggest supernatural agency should be rehabilitated and eventually included in the science curriculum. In these two distinct levels, the creationist claim is advanced as a logical implication of political liberalism's purported commitment to religious impartiality.