A Question Over Titles and Honorifics

I have a question that's been bugging me for a bit - 

I've heard plenty over using something along the lines of XY-はかせ for someone with a PhD, or XY-せんせい as a general way to speak to/about teachers - but I've never heard or haven't learned the titles for other roles, like medical doctors or members of clergy. 

Are there any titles similar to the English term "Pastor" [I.e. - Pastor XY], or any other job-specifc titles I should keep in mind before speaking to any professionals? Or is XY-さん polite enough to use when-in-doubt?

どうも有難うございます!