Religion has had an ambiguous role in Ontario public education, having provided both the common language for social cohesion and for resistance by religious groups to what they have perceived to be a dominant, exclusive and coercive ethos. In similar ways, religious freedom and diversity have been highly prized and protected in Ontario while at the same time being sources of anxiety and social disruption. Using critical discourse analysis and critical genealogical analysis I examine the conflicted role of religion in Ontario public education through competing discourses in political rhetoric, selected government documents formulating ways of conceptualizing the role of religion in public education from 1950 to 2003 and case law between 1985 and 1997. More precisely, I examine ways in which educational, social and political goals of education have been intertwined throughout the history of Ontario public education. I show that the public school system has been a state instrument privileged to deliver public education as a way to resolve the tension between social cohesion and social diversity by delivering common civic values. One result is that challenges to the public school system are often interpreted as attacks on public education and on Ontario society, particularly when those challenges are launched by religious groups. This has meant that debates about the role of religion in public education tend to be volatile making serious dialogue about this important social issue difficult to achieve while restricting the space for religious diversity in public education.