eading through this thread the primary issue is being missed, at least in my view. there is big difference between conveyence of personal expression, and government sponsored communication that potenially expresses a preference of religous conviction. In the US, there is a strong seperation of church/state culture/tradition, codified in the declaration of indepennce and at least on foreign treaty (alluded to previously). Individuals have a right to worship in the manner they choose, or to not worship at all. To assure those rights, all levels or government are oboliged to take care, actually resist, engaging in religous expression. Hence the issue around nativity scenes on public land, and ten commandments in government court houses.
As gio, indicated d previously, individual expression falls into a different category all together. I do not find it offensive, but others e may find it at least presumptuous in that it assumes the person you are speaking with believes in blessings are prayer, or christmas, or whatever. That is my view anyway.