Oh, absolutely.
Those kinds of phrases just drip of condescending enthusiasm. It's demeaning, demoralizing, and just plain mean-spirited. It's completely disrepectful of that individual (even on a humanistic level) to throw that in someone's face.
While, in one respect, those phrases may be sincere from a devout believer and it's being done as an act of one's faith, in another respect, it is throwing your beliefs in someone's face -and insulting them if you know their beliefs do not even remotely parallel yours.
If you MUST believe that you should "love" or "pray for" another person, what is the harm is doing so silently?
Saying anything to contradict those "I love you's" and "I'll pray for you's" adds fuel to the fire and reinforces the belief that you are, in fact, a heathen. With saying, "shut up", etc. you are reinforcing their beliefs because they will believe that, with that attitude, you must need to be prayed for and loved. Somehow your life is miserable without their God, bible, or Christ in it. Even though you know that's not true and that you don't lose sleep at night over it.
It's absolutely insulting to hear things like that from Christians.
There's really not much you can say in return or retaliation unless you want to sarcastically thank them, ignore them, laugh at them, or shake your head in disbelief.
I say you should take the higher road, even if it does enrage you to hear it.
If anyone else has a better idea of how to respond, I'm open to new ideas.