I don't see how this question is offensive at all.
I am Muslim first of all. So just to clarify my opinions aren't being put forth as someone who is a Christian or who is not aware of what it is like to be marginalized.
In fact I would argue that in our present political climate I face more open hostility as a Muslim then the average athiest.
That said I think you might be overreacting a bit to this. While you are certainly entitled to your own emotions and feelings, you DID sort of open this up for public input, thus I will give you my own opinion on the content of the original post. It's by no means meant to be personal or hostile.
Imagine a conversation that goes like this:
Charge Nurse: "Where are you from?"
New Nurse: "Texas!"
Charge Nurse: "Nice! Have you found any good Steak Houses around here yet?"
New Nurse: "No, I'll have you know I am a Vegan! Furthermore I find it very rude and unorofessional for you to assume that just because I am fron Texas I eat meat! The only conversation that belongs here is patient care and I would appreciate it if you left my personal life out of this!"
How would you view such a conversation as a third party observer? If you felt the new nurse overreacted in this scenario then you and I are on the same page!
While it is a bit presumptuous to assume that a new nurse is a Christian, the question itself is rather innocent. You are certainly welcome to inform the individual of your situation or simply inform them that, you orefer to keep that sort of stuff on the downlow. There are tactful ways to close the conversation.
However I don't think theres any need to really let it get under your skin either.
Nearly 75% of Americans are Christian, in nursing specifically studies have found that as many as 88% of Nurses are religious.
What about the doctors, sure there would,be alot of atheist doctors? Wrong!
There are actually LESS atheist doctors compared to the population at large! Doctors were also be discovered to be more likely to apply religion in the workspace as well. 55% of Physicians go so far as to openly admit that religious beliefs guide their patient care practice.
400 Bad Request
These numbers of course get higher in certain regions. In Mississippi for example Atheists constitute quite the minority.
In light of all these statistics, it is not necessarily shocking to me that questions about church preference come up. I can't see it being offensive, they are only trying to ensure you get settled in.