How to react to a student proselytising during office hours? A few weeks ago, a student asked me during my office hours whether I was religious or not. More specifically, he asked whether I believed in his religion, and was visibly disappointed when I replied negatively.

How should I react to a question such as this? Religion is a bit of a touchy subject, and even if I am a TA (i.e., not the instructor of the course - and more importantly, also a student), I don't want to be put in a similar situation again.

More generally speaking, how do I react to a situation in which I have to answer a question in a way that I know is likely to upset a student, without lying or making the situation worse?

edit: Some comments have pointed out that the student was never actually preaching, and I understand and somewhat agree. The reason I chose this phrasing over anything else was because he did try to make the conversation into something along the lines of "Do you want to learn about the ways of [religious figure]? There's always time, you know".

edit 2: I'm in computer science; there is no link whatsoever between religion and the contents of the class (or the whole program, really).
You address this by stating directly 


  "I would prefer not to discuss this topic during office hours. Can I help you with any questions you have on the homework?"


If the issue persists, I would speak with the professor and perhaps also your dean of students (or something similar).