I actually think we can make these potential issues worse by getting ahead of ourselves and making judgments based on seeing a crucifix on the wall, a star of david around the neck, certain dress or the like. Within any religious or cultural group is a wide spectrum of observance. My policy is to approach every patient contact with full professionalism and respect and let their actions and attitude dictate our interaction. If you jump the gun and assume certain behaviours out of a group that you're not fully familiar with you may end up offending someone by trying not to offend them.
I work in an incredibly diverse area with one of the largest populations of visual minorities in the country AND one of the largest populations of new Canadians.
You have a job to do that involves assessing and treating your patient. Do that with respect and be responsive to your patient and you should be fine.