How is it that religion has such a stronghold in society that it impedes over simple human rights?

For example, my last question was about speaking to muslim women in Canada who wear the veil. I want to talk, as long as they are aloud to or willing, about why they feel they should or need to wear it here in our westernized society. The plan was to be very respectful obviously, but then I got attack mail from Christians and others calling me a racist, a bigot, a f***head and a plethora of other insults, which all mean nothing to me.