How would Japanese people react to someone refusing to say “itadakimasu” for religious reasons?

So, it’s my understanding that in Japan it’s considered to be polite to say “itadakimasu” before eating. From what I’ve read, it seems that the meaning of this phrase derives from Buddhist and Shinto religious concepts, however, which gives rise to this question: how would the typical Japanese person respond to a foreigner (who might be a Christian, Muslim, or a member of some similar monotheistic faith) who refused to say it (as politely as possible) and cited religious reasons to do so?