What are you?

When since did it become a part of polite conversation to ask if you are a christian?
I have always held that one's religion is personal.  I teach this to my children also.  My daughter recently told me that she has been asked this question more than once recently, by other children.
I try to teach my children to think for themselves and to most importantly have respect not only for themselves but for others. 
Is this the new "what are you?" question?

Growing up, people would always ask me "what are you?", referring to race.  Started out I would answer in detail.  I had to explain the way I looked, my last name and that these two things were not unusual in Jamaica where I was born.  It became quite exhausting always having to explain myself.

 It was also a game between those who knew me and someone first meeting me.  The new person had to guess my background.  No one ever got it right.
Eventually I grew to resent the "what are you?" question.  What difference did it make? Why was a label so important?

I suppose now that we are in an age of post-racial (cough)conflict, religion will be "new" divide.
I do not think one's religious pursuits is a topic for chit-chat.  I especially do not think children are in the position the discuss religion.  It takes experience and understanding to evolve (yes evolve) into one's religious beliefs.  Children are simply regurgitating their adult influences. 
I understand this as a tactic, by using children to pose their views on other children it gives the illusion of being harmless.  It is peer pressure.  One child invites another to "Fall Fest" at their church, because it will be fun.  Not wanting to be left out, the child pleads with the parents to attend.  Next invitation is to a church service.  Then the indoctrination begins. 

Even as an adult I face similar invasive ploys on my religious practice.  I will meet someone and within the first conversation I am invited to their church.  I find this offensive.  Why is it assumed I want to attend their church? Or why is it assumed I do not have a church of my own? Does this usually work?  Upon meeting someone, because an invitation to church comes up, does everything prior to the meeting not count and now the invitation will be accepted and all will be well.

As an adult I am able to stand my ground and defend myself, but a child is not often equipped to handle such subtle influences.   
It seems now that parents are teaching their children that religious denomination is a prerequisite to friendship.  I can see where that will lead to more understanding, tolerance and acceptance.  I now have included "religious bullying" in my conversations on what are red flags in an unhealthy relationship with my 11 year old.