What if I was vegan? What if I was vegan and you weren't? Let's imagine that both of these things are true for a moment.
Not only are you not vegan, but you enjoy all the foods vegans don't eat. You are happy with the status quo and have no desire to change your diet.
I show up one day and demand that you become vegan. Why? Because of my religious beliefs. Based on these beliefs, I've decided that everybody should be vegan.