How much consideration would such arguments warrant from people who do not subscribe to the particular religion the argument is based in? Freedom of religion means that you should be free to disregard an argument that something should or should not be done based on whether or not it is consistent with someone else's relgious beiefs. You are under no particular civic duty to subscribe to or assume those beliefs. Rejecting a rational argument because you choose to be irrational seems a different matter.
There is no need to ponder "what if" scenarios. I have pointed to a specific example several times:
Proposition 8, where voters resoundingly voted against the leftist darling of "Homosexual Marriage" and we see a Judge declare the voters irrational because he feels that "Religious Belief" premised their votes.
I do not see Libertarians too concerned about this declaration of "irrational" -do you?