There are sound reasons for this: if a person behaves in a particular way that does not adhere to the norms of society dependent on his irrational religious or cultural personal beliefs he or she will try and justify his or her actions through lies and deception to his fellow human beings (thereby causing problems in society at large) as well as to the State authorities even in a court of law where he takes an oath upon his or her Holy book. These are very harmful and insidious in their impact on the need for a harmonised State. When people do something that is not normal they will try their best to escape justice, including keeping silent.
We all impact each others in what could be see as harmful ways. No getting around that, however civic laws are enforced by governments so we can coexist as best we can. Civic laws should be as blind as possible when it comes to religious beliefs.