INTERESTING TOPIC! look how diverse the opinions are on this string...now think -- the people reading your statement will be picked at random from a group like this. you will most likely have one or more person disagreeing with you. BUT! if you are a future doc type, and your religion is a deeply engrained part of why you are choosing to do medicine -- because of the nature of the profession -- you really would not be as truthful as possible in explaining why you chose medicine if you omitted it (likewise you'd be lying if you started to talk about it if you're an atheist). the people reading apps, regardless of their own beliefs, are obliged to be religion-blind, and will respect it if it is genuine.
HOWEVER, there is a right and wrong way to discuss religion in a PS and an interview -- although the statement and interview is all about you as an applicant, i think it's important to never put the interviewer/app reader in an uncomfortable place. ie, make the religious sentiment accessible to the best of your ability to others outside of your faith, stay focused on the relevance, and don't waste words belaboring it as a little goes a long way with such a thick topic.
that being said, i think some "higher reason" (love of mankind, obligation to others) is NECESSARY in medicine -- and should be mentioned!!!, but this is neither equal to, nor mutually exclusive from, religion. although i am agnostic/leaning very far towards atheism, i mentioned a religious concept (i wasn't bulls*****ing, of course) in my personal statement without mentioning G-d/gods/etc - and i did get asked about this in one of my interviews and spoke about the concept without delving into religion. this was my way of expressing my "higher reason" -- if you are concerned with alienating an interviewer/app reader...this might be the way to go...