Political liberals are primarily concerned with the roles played by the government and public schools in civic education. In policies related to religious schools, political liberals often use a strategy of regulation that aims to restrict religious schools. I argue that, although this strategy is effective in eliminating bad religious schools, it alone is unable to ensure that all (or most) reasonable citizens achieve full justification, which is a necessary condition for the stability of a just society. I, therefore, suggest that this strategy should be supplemented with a strategy of promotion. This strategy implies that a government should use policies, such as tax exemption, subsidy, national prize, and advertisement, to encourage good religious schools that teach students to reconcile religious beliefs and political ideas. While the government remains neutral and offers a citizenship curriculum that teaches political ideas, religious schools teach theological beliefs that provide students comprehensive reasons to affirm political ideas. This division of labor facilitates students from different religious backgrounds to attain full justification. Religious schools have often been regarded as posing a threat to cultural balkanization. It is, however, an overlooked grain of truth that religious schools could be essential cornerstones of a stable liberal democracy.