Gerald Gaus and Kevin Vallier, in their conclusion to a paper posted at Public Reason:
Our focus has been on “secular” and “religious” reasons, as so much of the debate has been framed in this way. We hope it is clear that, in the end, the analysis does not depend on making sense of this vexed distinction. Understanding public justification does not require classifying reasons into types — be it secular/religious, public/private, or political/comprehensive. Building on any such categorization seems a dubious enterprise. For purposes of meeting the Public Justification Principle what is important is whether a reason — be it “secular” or “religious” — is within the bounds of reasonable pluralism and how it enters into the network of the other such reasons. Moreover, we have stressed that it is an error to take a doctrine of what reasons can enter into the public justification of a law and to infer a doctrine of what reasons are appropriate in political debate. Doctrines that classify reasons into those that can be drawn upon and those that are excluded from the political life of a liberal polity lessen the resources for public justification, for doctrines of exclusion deplete the pool of reasons and information that can enter into the overall network that can justify laws to everyone. To be sure, it has seemed to some that excluding selected types of reasons from public justification and political life does, after all, further the cause of public justification: “private,” “sectarian,” “religious,” or “comprehensive” reasons will then be unable to block “secular,” “nonsectarian” proposals. The true cause of public justification, though, is to formulate laws that respect all as free and equal: this cause is not furthered by allowing some to impose laws on those who do not have sufficient reason to accept them.
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