How do citizens make sense of nanotechnology as more applications reach the market and the mainstream media start to debate the potential risks and benefits of technology(1)? As with many other political and scientific issues, citizens rely on cognitive shortcuts or heuristics to make sense of issues for which they have low levels of knowledge(2). These heuristics can include predispositional factors, such as ideological beliefs or value systems(3), and also short-term frames of reference provided by the media or other sources of information(4). Recent research suggests that 'religious filters' are an important heuristic for scientific issues in general(5), and nanotechnology in particular(6). A religious filter is more than a simple correlation between religiosity and attitudes toward science: it refers to a link between benefit perceptions and attitudes that varies depending on respondents' levels of religiosity. In surveys, seeing the benefits of nanotechnology is consistently linked to more positive attitudes about nanotechnology among less religious respondents, with this effect being significantly weaker for more religious respondents(6). For this study, we have combined public opinion surveys in the United States with Eurobarometer surveys about public attitudes toward nanotechnology in Europe to compare the influence of religious beliefs on attitudes towards nanotechnology in the United States and Europe. Our results show that respondents in the United States were significantly less likely to agree that nanotechnology is morally acceptable than respondents in many European countries. These moral views correlated directly with aggregate levels of religiosity in each country, even after controlling for national research productivity and measures of science performance for high-school students.