Why do some people refuse to grasp the concept of religious privacy?

I know how you feel because I also believe religion is a private and personal matter for myself. Since religion is mainly a group practice, and most religions advocate spreading their faith, it is difficult for people who consider their beliefs private or personal to deal with that. My close family members are Muslim and they occasionally reprimand me for not following rules, however, my beliefs align with Zoroastrian beliefs, and although I am in agreement with my Muslim family members on many of their beliefs as well, I prefer not to discuss or argue, but to maintain my personal spirituality, and freedom of choice. Most people just want to make sure you are doing what they approve of, I think its about power and control.