Some of my favorites:
-so you're choosing to go to hell? No, I'm choosing to be reincarnated, and hopefully attain enlightenment.
-You're a Buddhist? So, you like, worship the devil? No, Buddhists don't worship anything.
-God loves you. I should write an autobiography to prove that one wrong.
-I love you. That's only half a statement, the rest is, 'as long as you believe the way I do, otherwise, you can go to hell'.
-I'm sorry you're hungry, homeless, and can't find a job; I'll pray for you. Great, but what about helping me out with the needful things now?
-Without Jesus, you'll be in your sins. Sorry, I've found Buddhist ethics to be much more holy than xtian ethics.
-How could you leave xtianity? You must not have been saved to begin with. Fine, that doesn't bother me at all. (xtians actually say this to ex-xtians, hoping that it gets them angry enough to argue the point with them)
There's really just too many to list, and that's all I can think of for now.