I respect the ritual of the deceased family or even the wedding of that family. Just as I would want others to respect my rituals :) You don't have to participate but to just be there for the celebration at hand. That is what matters.

I did attend a mass for someone and I refrained from saying the prayers. A lady next to me said.. "Oh? Don't you know the words? Here is a pamphlet so you can read along." That made me very uncomfortable! I knew the words... but I chose not to say them.