My annoyance at the person who posted on the Interfaith list yesterday had nothing to do with the fact that he wished blessings from his Deity upon the project. Really! I have no problem with Christianity as such, or with any other religious belief or preference (so long as it doesn't attempt to impose itself on me). I don't view a blessing from another, a prayer, a "happy [fill in holiday here]," or any other type of well wishing, religious or not, as anything I should be offended by. It comes from their hearts. For all I know, they are bestowing upon me, the highest honor that they can think of; asking their Deity to bless me, a stranger, usually for a kindness, or even just because I exist in their world.
As illustration, when I was flying to NH, I received the special bonus prize of extra screening. Flight had been booked only hours before. I was flying without baggage, unaccompanied, and one way. Top it off, I was flying out of Washington National airport. They went all through my stuff, as usual, put me through the little puff chamber thing, etc. etc. One of the TSA officers asked me why I was flying one way. I told him that I had to get to Manchester because my mother was about to undergo surgery, it was serious, and I needed to be there. He asked me whether or not she would accept prayers. I was touched. This man who had never met me, sees me in connection with his job, and could have treated me like "just another passenger" instead offered prayers for my mother. I thought that was a wonderfully warm and human gesture, regardless of which Deity he will ultimately pray to on her behalf. I thanked him profusely and told him that indeed she would, and I appreciated it very much.
That little gesture out of this man's heart COULD have been treated with disdain. "What KIND of prayers" or "to WHAT God" or whatever, could have been thrown back in his face had I been a person who saw offense where the opposite was intended. But I truly feel that every little bit helps, and if his Deity, whichever that may be, sees fit to bless my mother and help her healing, I offer thanks, regardless of who that Deity is.
What I was upset by, and will always be upset by, is the assumption that I did not choose my religion with care and knowledge, and that I, or others, should instead convert to their religion. The wish that all, or members of a certain group, or individuals who are strangers, should blindly follow your path is something that is so alien and offensive to me, because it makes certain assumptions that I don't appreciate. The first is that "one size fits all." Not every religion is appropriate for each person. Second is the assumption that this person somehow knows better than you do what's best for your spiritual well being. Third is the idea that their religion is somehow "Truth" (capital T intentional) and yours is.... well.... not truth. Therefore, they are "here to help you." Gee, thanks :-).
So anyway, my point here is that I'm certainly not upset when others ask for their Deity(s)' blessing on me or mine. I DO, however, get upset when they advocate mass conversion to their religion.